Remove MemoryContextContains().

[pgsql.git] / src / backend / utils / mmgr / mcxt.c

/*-------------------------------------------------------------------------
 *
 * mcxt.c
 *        POSTGRES memory context management code.
 *
 * This module handles context management operations that are independent
 * of the particular kind of context being operated on.  It calls
 * context-type-specific operations via the function pointers in a
 * context's MemoryContextMethods struct.
 *
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/backend/utils/mmgr/mcxt.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/procsignal.h"
#include "utils/fmgrprotos.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_internal.h"


/*****************************************************************************
 *        GLOBAL MEMORY                                                                                                                  *
 *****************************************************************************/

static const MemoryContextMethods mcxt_methods[] = {
        /* aset.c */
        [MCTX_ASET_ID].alloc = AllocSetAlloc,
        [MCTX_ASET_ID].free_p = AllocSetFree,
        [MCTX_ASET_ID].realloc = AllocSetRealloc,
        [MCTX_ASET_ID].reset = AllocSetReset,
        [MCTX_ASET_ID].delete_context = AllocSetDelete,
        [MCTX_ASET_ID].get_chunk_context = AllocSetGetChunkContext,
        [MCTX_ASET_ID].get_chunk_space = AllocSetGetChunkSpace,
        [MCTX_ASET_ID].is_empty = AllocSetIsEmpty,
        [MCTX_ASET_ID].stats = AllocSetStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_ASET_ID].check = AllocSetCheck,
#endif

        /* generation.c */
        [MCTX_GENERATION_ID].alloc = GenerationAlloc,
        [MCTX_GENERATION_ID].free_p = GenerationFree,
        [MCTX_GENERATION_ID].realloc = GenerationRealloc,
        [MCTX_GENERATION_ID].reset = GenerationReset,
        [MCTX_GENERATION_ID].delete_context = GenerationDelete,
        [MCTX_GENERATION_ID].get_chunk_context = GenerationGetChunkContext,
        [MCTX_GENERATION_ID].get_chunk_space = GenerationGetChunkSpace,
        [MCTX_GENERATION_ID].is_empty = GenerationIsEmpty,
        [MCTX_GENERATION_ID].stats = GenerationStats,
#ifdef MEMORY_CONTEXT_CHECKING
        [MCTX_GENERATION_ID].check = GenerationCheck,
#endif

        /* slab.c */
        [MCTX_SLAB_ID].alloc = SlabAlloc,
        [MCTX_SLAB_ID].free_p = SlabFree,
        [MCTX_SLAB_ID].realloc = SlabRealloc,
        [MCTX_SLAB_ID].reset = SlabReset,
        [MCTX_SLAB_ID].delete_context = SlabDelete,
        [MCTX_SLAB_ID].get_chunk_context = SlabGetChunkContext,
        [MCTX_SLAB_ID].get_chunk_space = SlabGetChunkSpace,
        [MCTX_SLAB_ID].is_empty = SlabIsEmpty,
        [MCTX_SLAB_ID].stats = SlabStats
#ifdef MEMORY_CONTEXT_CHECKING
        ,[MCTX_SLAB_ID].check = SlabCheck
#endif
};

/*
 * CurrentMemoryContext
 *              Default memory context for allocations.
 */
MemoryContext CurrentMemoryContext = NULL;

/*
 * Standard top-level contexts. For a description of the purpose of each
 * of these contexts, refer to src/backend/utils/mmgr/README
 */
MemoryContext TopMemoryContext = NULL;
MemoryContext ErrorContext = NULL;
MemoryContext PostmasterContext = NULL;
MemoryContext CacheMemoryContext = NULL;
MemoryContext MessageContext = NULL;
MemoryContext TopTransactionContext = NULL;
MemoryContext CurTransactionContext = NULL;

/* This is a transient link to the active portal's memory context: */
MemoryContext PortalContext = NULL;

static void MemoryContextCallResetCallbacks(MemoryContext context);
static void MemoryContextStatsInternal(MemoryContext context, int level,
                                                                           bool print, int max_children,
                                                                           MemoryContextCounters *totals,
                                                                           bool print_to_stderr);
static void MemoryContextStatsPrint(MemoryContext context, void *passthru,
                                                                        const char *stats_string,
                                                                        bool print_to_stderr);

/*
 * You should not do memory allocations within a critical section, because
 * an out-of-memory error will be escalated to a PANIC. To enforce that
 * rule, the allocation functions Assert that.
 */
#define AssertNotInCriticalSection(context) \
        Assert(CritSectionCount == 0 || (context)->allowInCritSection)

/*
 * Call the given function in the MemoryContextMethods for the memory context
 * type that 'pointer' belongs to.
 */
#define MCXT_METHOD(pointer, method) \
        mcxt_methods[GetMemoryChunkMethodID(pointer)].method


/*****************************************************************************
 *        EXPORTED ROUTINES                                                                                                              *
 *****************************************************************************/


/*
 * MemoryContextInit
 *              Start up the memory-context subsystem.
 *
 * This must be called before creating contexts or allocating memory in
 * contexts.  TopMemoryContext and ErrorContext are initialized here;
 * other contexts must be created afterwards.
 *
 * In normal multi-backend operation, this is called once during
 * postmaster startup, and not at all by individual backend startup
 * (since the backends inherit an already-initialized context subsystem
 * by virtue of being forked off the postmaster).  But in an EXEC_BACKEND
 * build, each process must do this for itself.
 *
 * In a standalone backend this must be called during backend startup.
 */
void
MemoryContextInit(void)
{
        AssertState(TopMemoryContext == NULL);

        /*
         * First, initialize TopMemoryContext, which is the parent of all others.
         */
        TopMemoryContext = AllocSetContextCreate((MemoryContext) NULL,
                                                                                         "TopMemoryContext",
                                                                                         ALLOCSET_DEFAULT_SIZES);

        /*
         * Not having any other place to point CurrentMemoryContext, make it point
         * to TopMemoryContext.  Caller should change this soon!
         */
        CurrentMemoryContext = TopMemoryContext;

        /*
         * Initialize ErrorContext as an AllocSetContext with slow growth rate ---
         * we don't really expect much to be allocated in it. More to the point,
         * require it to contain at least 8K at all times. This is the only case
         * where retained memory in a context is *essential* --- we want to be
         * sure ErrorContext still has some memory even if we've run out
         * elsewhere! Also, allow allocations in ErrorContext within a critical
         * section. Otherwise a PANIC will cause an assertion failure in the error
         * reporting code, before printing out the real cause of the failure.
         *
         * This should be the last step in this function, as elog.c assumes memory
         * management works once ErrorContext is non-null.
         */
        ErrorContext = AllocSetContextCreate(TopMemoryContext,
                                                                                 "ErrorContext",
                                                                                 8 * 1024,
                                                                                 8 * 1024,
                                                                                 8 * 1024);
        MemoryContextAllowInCriticalSection(ErrorContext, true);
}

/*
 * MemoryContextReset
 *              Release all space allocated within a context and delete all its
 *              descendant contexts (but not the named context itself).
 */
void
MemoryContextReset(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));

        /* save a function call in common case where there are no children */
        if (context->firstchild != NULL)
                MemoryContextDeleteChildren(context);

        /* save a function call if no pallocs since startup or last reset */
        if (!context->isReset)
                MemoryContextResetOnly(context);
}

/*
 * MemoryContextResetOnly
 *              Release all space allocated within a context.
 *              Nothing is done to the context's descendant contexts.
 */
void
MemoryContextResetOnly(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));

        /* Nothing to do if no pallocs since startup or last reset */
        if (!context->isReset)
        {
                MemoryContextCallResetCallbacks(context);

                /*
                 * If context->ident points into the context's memory, it will become
                 * a dangling pointer.  We could prevent that by setting it to NULL
                 * here, but that would break valid coding patterns that keep the
                 * ident elsewhere, e.g. in a parent context.  So for now we assume
                 * the programmer got it right.
                 */

                context->methods->reset(context);
                context->isReset = true;
                VALGRIND_DESTROY_MEMPOOL(context);
                VALGRIND_CREATE_MEMPOOL(context, 0, false);
        }
}

/*
 * MemoryContextResetChildren
 *              Release all space allocated within a context's descendants,
 *              but don't delete the contexts themselves.  The named context
 *              itself is not touched.
 */
void
MemoryContextResetChildren(MemoryContext context)
{
        MemoryContext child;

        AssertArg(MemoryContextIsValid(context));

        for (child = context->firstchild; child != NULL; child = child->nextchild)
        {
                MemoryContextResetChildren(child);
                MemoryContextResetOnly(child);
        }
}

/*
 * MemoryContextDelete
 *              Delete a context and its descendants, and release all space
 *              allocated therein.
 *
 * The type-specific delete routine removes all storage for the context,
 * but we have to recurse to handle the children.
 * We must also delink the context from its parent, if it has one.
 */
void
MemoryContextDelete(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));
        /* We had better not be deleting TopMemoryContext ... */
        Assert(context != TopMemoryContext);
        /* And not CurrentMemoryContext, either */
        Assert(context != CurrentMemoryContext);

        /* save a function call in common case where there are no children */
        if (context->firstchild != NULL)
                MemoryContextDeleteChildren(context);

        /*
         * It's not entirely clear whether 'tis better to do this before or after
         * delinking the context; but an error in a callback will likely result in
         * leaking the whole context (if it's not a root context) if we do it
         * after, so let's do it before.
         */
        MemoryContextCallResetCallbacks(context);

        /*
         * We delink the context from its parent before deleting it, so that if
         * there's an error we won't have deleted/busted contexts still attached
         * to the context tree.  Better a leak than a crash.
         */
        MemoryContextSetParent(context, NULL);

        /*
         * Also reset the context's ident pointer, in case it points into the
         * context.  This would only matter if someone tries to get stats on the
         * (already unlinked) context, which is unlikely, but let's be safe.
         */
        context->ident = NULL;

        context->methods->delete_context(context);

        VALGRIND_DESTROY_MEMPOOL(context);
}

/*
 * MemoryContextDeleteChildren
 *              Delete all the descendants of the named context and release all
 *              space allocated therein.  The named context itself is not touched.
 */
void
MemoryContextDeleteChildren(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));

        /*
         * MemoryContextDelete will delink the child from me, so just iterate as
         * long as there is a child.
         */
        while (context->firstchild != NULL)
                MemoryContextDelete(context->firstchild);
}

/*
 * MemoryContextRegisterResetCallback
 *              Register a function to be called before next context reset/delete.
 *              Such callbacks will be called in reverse order of registration.
 *
 * The caller is responsible for allocating a MemoryContextCallback struct
 * to hold the info about this callback request, and for filling in the
 * "func" and "arg" fields in the struct to show what function to call with
 * what argument.  Typically the callback struct should be allocated within
 * the specified context, since that means it will automatically be freed
 * when no longer needed.
 *
 * There is no API for deregistering a callback once registered.  If you
 * want it to not do anything anymore, adjust the state pointed to by its
 * "arg" to indicate that.
 */
void
MemoryContextRegisterResetCallback(MemoryContext context,
                                                                   MemoryContextCallback *cb)
{
        AssertArg(MemoryContextIsValid(context));

        /* Push onto head so this will be called before older registrants. */
        cb->next = context->reset_cbs;
        context->reset_cbs = cb;
        /* Mark the context as non-reset (it probably is already). */
        context->isReset = false;
}

/*
 * MemoryContextCallResetCallbacks
 *              Internal function to call all registered callbacks for context.
 */
static void
MemoryContextCallResetCallbacks(MemoryContext context)
{
        MemoryContextCallback *cb;

        /*
         * We pop each callback from the list before calling.  That way, if an
         * error occurs inside the callback, we won't try to call it a second time
         * in the likely event that we reset or delete the context later.
         */
        while ((cb = context->reset_cbs) != NULL)
        {
                context->reset_cbs = cb->next;
                cb->func(cb->arg);
        }
}

/*
 * MemoryContextSetIdentifier
 *              Set the identifier string for a memory context.
 *
 * An identifier can be provided to help distinguish among different contexts
 * of the same kind in memory context stats dumps.  The identifier string
 * must live at least as long as the context it is for; typically it is
 * allocated inside that context, so that it automatically goes away on
 * context deletion.  Pass id = NULL to forget any old identifier.
 */
void
MemoryContextSetIdentifier(MemoryContext context, const char *id)
{
        AssertArg(MemoryContextIsValid(context));
        context->ident = id;
}

/*
 * MemoryContextSetParent
 *              Change a context to belong to a new parent (or no parent).
 *
 * We provide this as an API function because it is sometimes useful to
 * change a context's lifespan after creation.  For example, a context
 * might be created underneath a transient context, filled with data,
 * and then reparented underneath CacheMemoryContext to make it long-lived.
 * In this way no special effort is needed to get rid of the context in case
 * a failure occurs before its contents are completely set up.
 *
 * Callers often assume that this function cannot fail, so don't put any
 * elog(ERROR) calls in it.
 *
 * A possible caller error is to reparent a context under itself, creating
 * a loop in the context graph.  We assert here that context != new_parent,
 * but checking for multi-level loops seems more trouble than it's worth.
 */
void
MemoryContextSetParent(MemoryContext context, MemoryContext new_parent)
{
        AssertArg(MemoryContextIsValid(context));
        AssertArg(context != new_parent);

        /* Fast path if it's got correct parent already */
        if (new_parent == context->parent)
                return;

        /* Delink from existing parent, if any */
        if (context->parent)
        {
                MemoryContext parent = context->parent;

                if (context->prevchild != NULL)
                        context->prevchild->nextchild = context->nextchild;
                else
                {
                        Assert(parent->firstchild == context);
                        parent->firstchild = context->nextchild;
                }

                if (context->nextchild != NULL)
                        context->nextchild->prevchild = context->prevchild;
        }

        /* And relink */
        if (new_parent)
        {
                AssertArg(MemoryContextIsValid(new_parent));
                context->parent = new_parent;
                context->prevchild = NULL;
                context->nextchild = new_parent->firstchild;
                if (new_parent->firstchild != NULL)
                        new_parent->firstchild->prevchild = context;
                new_parent->firstchild = context;
        }
        else
        {
                context->parent = NULL;
                context->prevchild = NULL;
                context->nextchild = NULL;
        }
}

/*
 * MemoryContextAllowInCriticalSection
 *              Allow/disallow allocations in this memory context within a critical
 *              section.
 *
 * Normally, memory allocations are not allowed within a critical section,
 * because a failure would lead to PANIC.  There are a few exceptions to
 * that, like allocations related to debugging code that is not supposed to
 * be enabled in production.  This function can be used to exempt specific
 * memory contexts from the assertion in palloc().
 */
void
MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
{
        AssertArg(MemoryContextIsValid(context));

        context->allowInCritSection = allow;
}

/*
 * GetMemoryChunkContext
 *              Given a currently-allocated chunk, determine the MemoryContext that
 *              the chunk belongs to.
 */
MemoryContext
GetMemoryChunkContext(void *pointer)
{
        return MCXT_METHOD(pointer, get_chunk_context) (pointer);
}

/*
 * GetMemoryChunkSpace
 *              Given a currently-allocated chunk, determine the total space
 *              it occupies (including all memory-allocation overhead).
 *
 * This is useful for measuring the total space occupied by a set of
 * allocated chunks.
 */
Size
GetMemoryChunkSpace(void *pointer)
{
        return MCXT_METHOD(pointer, get_chunk_space) (pointer);
}

/*
 * MemoryContextGetParent
 *              Get the parent context (if any) of the specified context
 */
MemoryContext
MemoryContextGetParent(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));

        return context->parent;
}

/*
 * MemoryContextIsEmpty
 *              Is a memory context empty of any allocated space?
 */
bool
MemoryContextIsEmpty(MemoryContext context)
{
        AssertArg(MemoryContextIsValid(context));

        /*
         * For now, we consider a memory context nonempty if it has any children;
         * perhaps this should be changed later.
         */
        if (context->firstchild != NULL)
                return false;
        /* Otherwise use the type-specific inquiry */
        return context->methods->is_empty(context);
}

/*
 * Find the memory allocated to blocks for this memory context. If recurse is
 * true, also include children.
 */
Size
MemoryContextMemAllocated(MemoryContext context, bool recurse)
{
        Size            total = context->mem_allocated;

        AssertArg(MemoryContextIsValid(context));

        if (recurse)
        {
                MemoryContext child;

                for (child = context->firstchild;
                         child != NULL;
                         child = child->nextchild)
                        total += MemoryContextMemAllocated(child, true);
        }

        return total;
}

/*
 * MemoryContextStats
 *              Print statistics about the named context and all its descendants.
 *
 * This is just a debugging utility, so it's not very fancy.  However, we do
 * make some effort to summarize when the output would otherwise be very long.
 * The statistics are sent to stderr.
 */
void
MemoryContextStats(MemoryContext context)
{
        /* A hard-wired limit on the number of children is usually good enough */
        MemoryContextStatsDetail(context, 100, true);
}

/*
 * MemoryContextStatsDetail
 *
 * Entry point for use if you want to vary the number of child contexts shown.
 *
 * If print_to_stderr is true, print statistics about the memory contexts
 * with fprintf(stderr), otherwise use ereport().
 */
void
MemoryContextStatsDetail(MemoryContext context, int max_children,
                                                 bool print_to_stderr)
{
        MemoryContextCounters grand_totals;

        memset(&grand_totals, 0, sizeof(grand_totals));

        MemoryContextStatsInternal(context, 0, true, max_children, &grand_totals, print_to_stderr);

        if (print_to_stderr)
                fprintf(stderr,
                                "Grand total: %zu bytes in %zu blocks; %zu free (%zu chunks); %zu used\n",
                                grand_totals.totalspace, grand_totals.nblocks,
                                grand_totals.freespace, grand_totals.freechunks,
                                grand_totals.totalspace - grand_totals.freespace);
        else

                /*
                 * Use LOG_SERVER_ONLY to prevent the memory contexts from being sent
                 * to the connected client.
                 *
                 * We don't buffer the information about all memory contexts in a
                 * backend into StringInfo and log it as one message. Otherwise which
                 * may require the buffer to be enlarged very much and lead to OOM
                 * error since there can be a large number of memory contexts in a
                 * backend. Instead, we log one message per memory context.
                 */
                ereport(LOG_SERVER_ONLY,
                                (errhidestmt(true),
                                 errhidecontext(true),
                                 errmsg_internal("Grand total: %zu bytes in %zu blocks; %zu free (%zu chunks); %zu used",
                                                                 grand_totals.totalspace, grand_totals.nblocks,
                                                                 grand_totals.freespace, grand_totals.freechunks,
                                                                 grand_totals.totalspace - grand_totals.freespace)));
}

/*
 * MemoryContextStatsInternal
 *              One recursion level for MemoryContextStats
 *
 * Print this context if print is true, but in any case accumulate counts into
 * *totals (if given).
 */
static void
MemoryContextStatsInternal(MemoryContext context, int level,
                                                   bool print, int max_children,
                                                   MemoryContextCounters *totals,
                                                   bool print_to_stderr)
{
        MemoryContextCounters local_totals;
        MemoryContext child;
        int                     ichild;

        AssertArg(MemoryContextIsValid(context));

        /* Examine the context itself */
        context->methods->stats(context,
                                                        print ? MemoryContextStatsPrint : NULL,
                                                        (void *) &level,
                                                        totals, print_to_stderr);

        /*
         * Examine children.  If there are more than max_children of them, we do
         * not print the rest explicitly, but just summarize them.
         */
        memset(&local_totals, 0, sizeof(local_totals));

        for (child = context->firstchild, ichild = 0;
                 child != NULL;
                 child = child->nextchild, ichild++)
        {
                if (ichild < max_children)
                        MemoryContextStatsInternal(child, level + 1,
                                                                           print, max_children,
                                                                           totals,
                                                                           print_to_stderr);
                else
                        MemoryContextStatsInternal(child, level + 1,
                                                                           false, max_children,
                                                                           &local_totals,
                                                                           print_to_stderr);
        }

        /* Deal with excess children */
        if (ichild > max_children)
        {
                if (print)
                {
                        if (print_to_stderr)
                        {
                                int                     i;

                                for (i = 0; i <= level; i++)
                                        fprintf(stderr, "  ");
                                fprintf(stderr,
                                                "%d more child contexts containing %zu total in %zu blocks; %zu free (%zu chunks); %zu used\n",
                                                ichild - max_children,
                                                local_totals.totalspace,
                                                local_totals.nblocks,
                                                local_totals.freespace,
                                                local_totals.freechunks,
                                                local_totals.totalspace - local_totals.freespace);
                        }
                        else
                                ereport(LOG_SERVER_ONLY,
                                                (errhidestmt(true),
                                                 errhidecontext(true),
                                                 errmsg_internal("level: %d; %d more child contexts containing %zu total in %zu blocks; %zu free (%zu chunks); %zu used",
                                                                                 level,
                                                                                 ichild - max_children,
                                                                                 local_totals.totalspace,
                                                                                 local_totals.nblocks,
                                                                                 local_totals.freespace,
                                                                                 local_totals.freechunks,
                                                                                 local_totals.totalspace - local_totals.freespace)));
                }

                if (totals)
                {
                        totals->nblocks += local_totals.nblocks;
                        totals->freechunks += local_totals.freechunks;
                        totals->totalspace += local_totals.totalspace;
                        totals->freespace += local_totals.freespace;
                }
        }
}

/*
 * MemoryContextStatsPrint
 *              Print callback used by MemoryContextStatsInternal
 *
 * For now, the passthru pointer just points to "int level"; later we might
 * make that more complicated.
 */
static void
MemoryContextStatsPrint(MemoryContext context, void *passthru,
                                                const char *stats_string,
                                                bool print_to_stderr)
{
        int                     level = *(int *) passthru;
        const char *name = context->name;
        const char *ident = context->ident;
        char            truncated_ident[110];
        int                     i;

        /*
         * It seems preferable to label dynahash contexts with just the hash table
         * name.  Those are already unique enough, so the "dynahash" part isn't
         * very helpful, and this way is more consistent with pre-v11 practice.
         */
        if (ident && strcmp(name, "dynahash") == 0)
        {
                name = ident;
                ident = NULL;
        }

        truncated_ident[0] = '\0';

        if (ident)
        {
                /*
                 * Some contexts may have very long identifiers (e.g., SQL queries).
                 * Arbitrarily truncate at 100 bytes, but be careful not to break
                 * multibyte characters.  Also, replace ASCII control characters, such
                 * as newlines, with spaces.
                 */
                int                     idlen = strlen(ident);
                bool            truncated = false;

                strcpy(truncated_ident, ": ");
                i = strlen(truncated_ident);

                if (idlen > 100)
                {
                        idlen = pg_mbcliplen(ident, idlen, 100);
                        truncated = true;
                }

                while (idlen-- > 0)
                {
                        unsigned char c = *ident++;

                        if (c < ' ')
                                c = ' ';
                        truncated_ident[i++] = c;
                }
                truncated_ident[i] = '\0';

                if (truncated)
                        strcat(truncated_ident, "...");
        }

        if (print_to_stderr)
        {
                for (i = 0; i < level; i++)
                        fprintf(stderr, "  ");
                fprintf(stderr, "%s: %s%s\n", name, stats_string, truncated_ident);
        }
        else
                ereport(LOG_SERVER_ONLY,
                                (errhidestmt(true),
                                 errhidecontext(true),
                                 errmsg_internal("level: %d; %s: %s%s",
                                                                 level, name, stats_string, truncated_ident)));
}

/*
 * MemoryContextCheck
 *              Check all chunks in the named context.
 *
 * This is just a debugging utility, so it's not fancy.
 */
#ifdef MEMORY_CONTEXT_CHECKING
void
MemoryContextCheck(MemoryContext context)
{
        MemoryContext child;

        AssertArg(MemoryContextIsValid(context));

        context->methods->check(context);
        for (child = context->firstchild; child != NULL; child = child->nextchild)
                MemoryContextCheck(child);
}
#endif

/*
 * MemoryContextCreate
 *              Context-type-independent part of context creation.
 *
 * This is only intended to be called by context-type-specific
 * context creation routines, not by the unwashed masses.
 *
 * The memory context creation procedure goes like this:
 *      1.  Context-type-specific routine makes some initial space allocation,
 *              including enough space for the context header.  If it fails,
 *              it can ereport() with no damage done.
 *      2.      Context-type-specific routine sets up all type-specific fields of
 *              the header (those beyond MemoryContextData proper), as well as any
 *              other management fields it needs to have a fully valid context.
 *              Usually, failure in this step is impossible, but if it's possible
 *              the initial space allocation should be freed before ereport'ing.
 *      3.      Context-type-specific routine calls MemoryContextCreate() to fill in
 *              the generic header fields and link the context into the context tree.
 *      4.  We return to the context-type-specific routine, which finishes
 *              up type-specific initialization.  This routine can now do things
 *              that might fail (like allocate more memory), so long as it's
 *              sure the node is left in a state that delete will handle.
 *
 * node: the as-yet-uninitialized common part of the context header node.
 * tag: NodeTag code identifying the memory context type.
 * method_id: MemoryContextMethodID of the context-type being created.
 * parent: parent context, or NULL if this will be a top-level context.
 * name: name of context (must be statically allocated).
 *
 * Context routines generally assume that MemoryContextCreate can't fail,
 * so this can contain Assert but not elog/ereport.
 */
void
MemoryContextCreate(MemoryContext node,
                                        NodeTag tag,
                                        MemoryContextMethodID method_id,
                                        MemoryContext parent,
                                        const char *name)
{
        /* Creating new memory contexts is not allowed in a critical section */
        Assert(CritSectionCount == 0);

        /* Initialize all standard fields of memory context header */
        node->type = tag;
        node->isReset = true;
        node->methods = &mcxt_methods[method_id];
        node->parent = parent;
        node->firstchild = NULL;
        node->mem_allocated = 0;
        node->prevchild = NULL;
        node->name = name;
        node->ident = NULL;
        node->reset_cbs = NULL;

        /* OK to link node into context tree */
        if (parent)
        {
                node->nextchild = parent->firstchild;
                if (parent->firstchild != NULL)
                        parent->firstchild->prevchild = node;
                parent->firstchild = node;
                /* inherit allowInCritSection flag from parent */
                node->allowInCritSection = parent->allowInCritSection;
        }
        else
        {
                node->nextchild = NULL;
                node->allowInCritSection = false;
        }

        VALGRIND_CREATE_MEMPOOL(node, 0, false);
}

/*
 * MemoryContextAlloc
 *              Allocate space within the specified context.
 *
 * This could be turned into a macro, but we'd have to import
 * nodes/memnodes.h into postgres.h which seems a bad idea.
 */
void *
MemoryContextAlloc(MemoryContext context, Size size)
{
        void       *ret;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);

                /*
                 * Here, and elsewhere in this module, we show the target context's
                 * "name" but not its "ident" (if any) in user-visible error messages.
                 * The "ident" string might contain security-sensitive data, such as
                 * values in SQL commands.
                 */
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

/*
 * MemoryContextAllocZero
 *              Like MemoryContextAlloc, but clears allocated memory
 *
 *      We could just call MemoryContextAlloc then clear the memory, but this
 *      is a very common combination, so we provide the combined operation.
 */
void *
MemoryContextAllocZero(MemoryContext context, Size size)
{
        void       *ret;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * MemoryContextAllocZeroAligned
 *              MemoryContextAllocZero where length is suitable for MemSetLoop
 *
 *      This might seem overly specialized, but it's not because newNode()
 *      is so often called with compile-time-constant sizes.
 */
void *
MemoryContextAllocZeroAligned(MemoryContext context, Size size)
{
        void       *ret;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        MemSetLoop(ret, 0, size);

        return ret;
}

/*
 * MemoryContextAllocExtended
 *              Allocate space within the specified context using the given flags.
 */
void *
MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
{
        void       *ret;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (((flags & MCXT_ALLOC_HUGE) != 0 && !AllocHugeSizeIsValid(size)) ||
                ((flags & MCXT_ALLOC_HUGE) == 0 && !AllocSizeIsValid(size)))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                if ((flags & MCXT_ALLOC_NO_OOM) == 0)
                {
                        MemoryContextStats(TopMemoryContext);
                        ereport(ERROR,
                                        (errcode(ERRCODE_OUT_OF_MEMORY),
                                         errmsg("out of memory"),
                                         errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                           size, context->name)));
                }
                return NULL;
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        if ((flags & MCXT_ALLOC_ZERO) != 0)
                MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * HandleLogMemoryContextInterrupt
 *              Handle receipt of an interrupt indicating logging of memory
 *              contexts.
 *
 * All the actual work is deferred to ProcessLogMemoryContextInterrupt(),
 * because we cannot safely emit a log message inside the signal handler.
 */
void
HandleLogMemoryContextInterrupt(void)
{
        InterruptPending = true;
        LogMemoryContextPending = true;
        /* latch will be set by procsignal_sigusr1_handler */
}

/*
 * ProcessLogMemoryContextInterrupt
 *              Perform logging of memory contexts of this backend process.
 *
 * Any backend that participates in ProcSignal signaling must arrange
 * to call this function if we see LogMemoryContextPending set.
 * It is called from CHECK_FOR_INTERRUPTS(), which is enough because
 * the target process for logging of memory contexts is a backend.
 */
void
ProcessLogMemoryContextInterrupt(void)
{
        LogMemoryContextPending = false;

        /*
         * Use LOG_SERVER_ONLY to prevent this message from being sent to the
         * connected client.
         */
        ereport(LOG_SERVER_ONLY,
                        (errhidestmt(true),
                         errhidecontext(true),
                         errmsg("logging memory contexts of PID %d", MyProcPid)));

        /*
         * When a backend process is consuming huge memory, logging all its memory
         * contexts might overrun available disk space. To prevent this, we limit
         * the number of child contexts to log per parent to 100.
         *
         * As with MemoryContextStats(), we suppose that practical cases where the
         * dump gets long will typically be huge numbers of siblings under the
         * same parent context; while the additional debugging value from seeing
         * details about individual siblings beyond 100 will not be large.
         */
        MemoryContextStatsDetail(TopMemoryContext, 100, false);
}

void *
palloc(Size size)
{
        /* duplicates MemoryContextAlloc to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

void *
palloc0(Size size)
{
        /* duplicates MemoryContextAllocZero to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        MemSetAligned(ret, 0, size);

        return ret;
}

void *
palloc_extended(Size size, int flags)
{
        /* duplicates MemoryContextAllocExtended to avoid increased overhead */
        void       *ret;
        MemoryContext context = CurrentMemoryContext;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (((flags & MCXT_ALLOC_HUGE) != 0 && !AllocHugeSizeIsValid(size)) ||
                ((flags & MCXT_ALLOC_HUGE) == 0 && !AllocSizeIsValid(size)))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                if ((flags & MCXT_ALLOC_NO_OOM) == 0)
                {
                        MemoryContextStats(TopMemoryContext);
                        ereport(ERROR,
                                        (errcode(ERRCODE_OUT_OF_MEMORY),
                                         errmsg("out of memory"),
                                         errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                           size, context->name)));
                }
                return NULL;
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        if ((flags & MCXT_ALLOC_ZERO) != 0)
                MemSetAligned(ret, 0, size);

        return ret;
}

/*
 * pfree
 *              Release an allocated chunk.
 */
void
pfree(void *pointer)
{
#ifdef USE_VALGRIND
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif

        MCXT_METHOD(pointer, free_p) (pointer);
        VALGRIND_MEMPOOL_FREE(context, pointer);
}

/*
 * repalloc
 *              Adjust the size of a previously allocated chunk.
 */
void *
repalloc(void *pointer, Size size)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif
        void       *ret;

        if (!AllocSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        AssertNotInCriticalSection(context);

        /* isReset must be false already */
        Assert(!context->isReset);

        ret = MCXT_METHOD(pointer, realloc) (pointer, size);
        if (unlikely(ret == NULL))
        {
                MemoryContext cxt = GetMemoryChunkContext(pointer);

                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, cxt->name)));
        }

        VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);

        return ret;
}

/*
 * MemoryContextAllocHuge
 *              Allocate (possibly-expansive) space within the specified context.
 *
 * See considerations in comment at MaxAllocHugeSize.
 */
void *
MemoryContextAllocHuge(MemoryContext context, Size size)
{
        void       *ret;

        AssertArg(MemoryContextIsValid(context));
        AssertNotInCriticalSection(context);

        if (!AllocHugeSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        context->isReset = false;

        ret = context->methods->alloc(context, size);
        if (unlikely(ret == NULL))
        {
                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, context->name)));
        }

        VALGRIND_MEMPOOL_ALLOC(context, ret, size);

        return ret;
}

/*
 * repalloc_huge
 *              Adjust the size of a previously allocated chunk, permitting a large
 *              value.  The previous allocation need not have been "huge".
 */
void *
repalloc_huge(void *pointer, Size size)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
        MemoryContext context = GetMemoryChunkContext(pointer);
#endif
        void       *ret;

        if (!AllocHugeSizeIsValid(size))
                elog(ERROR, "invalid memory alloc request size %zu", size);

        AssertNotInCriticalSection(context);

        /* isReset must be false already */
        Assert(!context->isReset);

        ret = MCXT_METHOD(pointer, realloc) (pointer, size);
        if (unlikely(ret == NULL))
        {
                MemoryContext cxt = GetMemoryChunkContext(pointer);

                MemoryContextStats(TopMemoryContext);
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory"),
                                 errdetail("Failed on request of size %zu in memory context \"%s\".",
                                                   size, cxt->name)));
        }

        VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);

        return ret;
}

/*
 * MemoryContextStrdup
 *              Like strdup(), but allocate from the specified context
 */
char *
MemoryContextStrdup(MemoryContext context, const char *string)
{
        char       *nstr;
        Size            len = strlen(string) + 1;

        nstr = (char *) MemoryContextAlloc(context, len);

        memcpy(nstr, string, len);

        return nstr;
}

char *
pstrdup(const char *in)
{
        return MemoryContextStrdup(CurrentMemoryContext, in);
}

/*
 * pnstrdup
 *              Like pstrdup(), but append null byte to a
 *              not-necessarily-null-terminated input string.
 */
char *
pnstrdup(const char *in, Size len)
{
        char       *out;

        len = strnlen(in, len);

        out = palloc(len + 1);
        memcpy(out, in, len);
        out[len] = '\0';

        return out;
}

/*
 * Make copy of string with all trailing newline characters removed.
 */
char *
pchomp(const char *in)
{
        size_t          n;

        n = strlen(in);
        while (n > 0 && in[n - 1] == '\n')
                n--;
        return pnstrdup(in, n);
}