s3: Avoid a thundering herd in g_lock_unlock

[Samba.git] / lib / tsocket / tsocket_helpers.c

/*
   Unix SMB/CIFS implementation.

   Copyright (C) Stefan Metzmacher 2009

     ** NOTE! The following LGPL license applies to the tsocket
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/filesys.h"
#include "tsocket.h"
#include "tsocket_internal.h"

struct tdgram_sendto_queue_state {
        /* this structs are owned by the caller */
        struct {
                struct tevent_context *ev;
                struct tdgram_context *dgram;
                const uint8_t *buf;
                size_t len;
                const struct tsocket_address *dst;
        } caller;
        ssize_t ret;
};

static void tdgram_sendto_queue_trigger(struct tevent_req *req,
                                         void *private_data);
static void tdgram_sendto_queue_done(struct tevent_req *subreq);

/**
 * @brief Queue a dgram blob for sending through the socket
 * @param[in] mem_ctx   The memory context for the result
 * @param[in] ev        The event context the operation should work on
 * @param[in] dgram     The tdgram_context to send the message buffer
 * @param[in] queue     The existing dgram queue
 * @param[in] buf       The message buffer
 * @param[in] len       The message length
 * @param[in] dst       The destination socket address
 * @retval              The async request handle
 *
 * This function queues a blob for sending to destination through an existing
 * dgram socket. The async callback is triggered when the whole blob is
 * delivered to the underlying system socket.
 *
 * The caller needs to make sure that all non-scalar input parameters hang
 * arround for the whole lifetime of the request.
 */
struct tevent_req *tdgram_sendto_queue_send(TALLOC_CTX *mem_ctx,
                                            struct tevent_context *ev,
                                            struct tdgram_context *dgram,
                                            struct tevent_queue *queue,
                                            const uint8_t *buf,
                                            size_t len,
                                            struct tsocket_address *dst)
{
        struct tevent_req *req;
        struct tdgram_sendto_queue_state *state;
        bool ok;

        req = tevent_req_create(mem_ctx, &state,
                                struct tdgram_sendto_queue_state);
        if (!req) {
                return NULL;
        }

        state->caller.ev        = ev;
        state->caller.dgram     = dgram;
        state->caller.buf       = buf;
        state->caller.len       = len;
        state->caller.dst       = dst;
        state->ret              = -1;

        ok = tevent_queue_add(queue,
                              ev,
                              req,
                              tdgram_sendto_queue_trigger,
                              NULL);
        if (!ok) {
                tevent_req_nomem(NULL, req);
                goto post;
        }

        return req;

 post:
        tevent_req_post(req, ev);
        return req;
}

static void tdgram_sendto_queue_trigger(struct tevent_req *req,
                                         void *private_data)
{
        struct tdgram_sendto_queue_state *state = tevent_req_data(req,
                                        struct tdgram_sendto_queue_state);
        struct tevent_req *subreq;

        subreq = tdgram_sendto_send(state,
                                    state->caller.ev,
                                    state->caller.dgram,
                                    state->caller.buf,
                                    state->caller.len,
                                    state->caller.dst);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, tdgram_sendto_queue_done, req);
}

static void tdgram_sendto_queue_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(subreq,
                                 struct tevent_req);
        struct tdgram_sendto_queue_state *state = tevent_req_data(req,
                                        struct tdgram_sendto_queue_state);
        ssize_t ret;
        int sys_errno;

        ret = tdgram_sendto_recv(subreq, &sys_errno);
        talloc_free(subreq);
        if (ret == -1) {
                tevent_req_error(req, sys_errno);
                return;
        }
        state->ret = ret;

        tevent_req_done(req);
}

ssize_t tdgram_sendto_queue_recv(struct tevent_req *req, int *perrno)
{
        struct tdgram_sendto_queue_state *state = tevent_req_data(req,
                                        struct tdgram_sendto_queue_state);
        ssize_t ret;

        ret = tsocket_simple_int_recv(req, perrno);
        if (ret == 0) {
                ret = state->ret;
        }

        tevent_req_received(req);
        return ret;
}

struct tstream_readv_pdu_state {
        /* this structs are owned by the caller */
        struct {
                struct tevent_context *ev;
                struct tstream_context *stream;
                tstream_readv_pdu_next_vector_t next_vector_fn;
                void *next_vector_private;
        } caller;

        /*
         * Each call to the callback resets iov and count
         * the callback allocated the iov as child of our state,
         * that means we are allowed to modify and free it.
         *
         * we should call the callback every time we filled the given
         * vector and ask for a new vector. We return if the callback
         * ask for 0 bytes.
         */
        struct iovec *vector;
        size_t count;

        /*
         * the total number of bytes we read,
         * the return value of the _recv function
         */
        int total_read;
};

static void tstream_readv_pdu_ask_for_next_vector(struct tevent_req *req);
static void tstream_readv_pdu_readv_done(struct tevent_req *subreq);

struct tevent_req *tstream_readv_pdu_send(TALLOC_CTX *mem_ctx,
                                struct tevent_context *ev,
                                struct tstream_context *stream,
                                tstream_readv_pdu_next_vector_t next_vector_fn,
                                void *next_vector_private)
{
        struct tevent_req *req;
        struct tstream_readv_pdu_state *state;

        req = tevent_req_create(mem_ctx, &state,
                                struct tstream_readv_pdu_state);
        if (!req) {
                return NULL;
        }

        state->caller.ev                        = ev;
        state->caller.stream                    = stream;
        state->caller.next_vector_fn            = next_vector_fn;
        state->caller.next_vector_private       = next_vector_private;

        state->vector           = NULL;
        state->count            = 0;
        state->total_read       = 0;

        tstream_readv_pdu_ask_for_next_vector(req);
        if (!tevent_req_is_in_progress(req)) {
                goto post;
        }

        return req;

 post:
        return tevent_req_post(req, ev);
}

static void tstream_readv_pdu_ask_for_next_vector(struct tevent_req *req)
{
        struct tstream_readv_pdu_state *state = tevent_req_data(req,
                                            struct tstream_readv_pdu_state);
        int ret;
        size_t to_read = 0;
        size_t i;
        struct tevent_req *subreq;

        TALLOC_FREE(state->vector);
        state->count = 0;

        ret = state->caller.next_vector_fn(state->caller.stream,
                                           state->caller.next_vector_private,
                                           state, &state->vector, &state->count);
        if (ret == -1) {
                tevent_req_error(req, errno);
                return;
        }

        if (state->count == 0) {
                tevent_req_done(req);
                return;
        }

        for (i=0; i < state->count; i++) {
                size_t tmp = to_read;
                tmp += state->vector[i].iov_len;

                if (tmp < to_read) {
                        tevent_req_error(req, EMSGSIZE);
                        return;
                }

                to_read = tmp;
        }

        /*
         * this is invalid the next vector function should have
         * reported count == 0.
         */
        if (to_read == 0) {
                tevent_req_error(req, EINVAL);
                return;
        }

        if (state->total_read + to_read < state->total_read) {
                tevent_req_error(req, EMSGSIZE);
                return;
        }

        subreq = tstream_readv_send(state,
                                    state->caller.ev,
                                    state->caller.stream,
                                    state->vector,
                                    state->count);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, tstream_readv_pdu_readv_done, req);
}

static void tstream_readv_pdu_readv_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(subreq,
                                 struct tevent_req);
        struct tstream_readv_pdu_state *state = tevent_req_data(req,
                                            struct tstream_readv_pdu_state);
        int ret;
        int sys_errno;

        ret = tstream_readv_recv(subreq, &sys_errno);
        if (ret == -1) {
                tevent_req_error(req, sys_errno);
                return;
        }

        state->total_read += ret;

        /* ask the callback for a new vector we should fill */
        tstream_readv_pdu_ask_for_next_vector(req);
}

int tstream_readv_pdu_recv(struct tevent_req *req, int *perrno)
{
        struct tstream_readv_pdu_state *state = tevent_req_data(req,
                                            struct tstream_readv_pdu_state);
        int ret;

        ret = tsocket_simple_int_recv(req, perrno);
        if (ret == 0) {
                ret = state->total_read;
        }

        tevent_req_received(req);
        return ret;
}

struct tstream_readv_pdu_queue_state {
        /* this structs are owned by the caller */
        struct {
                struct tevent_context *ev;
                struct tstream_context *stream;
                tstream_readv_pdu_next_vector_t next_vector_fn;
                void *next_vector_private;
        } caller;
        int ret;
};

static void tstream_readv_pdu_queue_trigger(struct tevent_req *req,
                                         void *private_data);
static void tstream_readv_pdu_queue_done(struct tevent_req *subreq);

/**
 * @brief Queue a dgram blob for sending through the socket
 * @param[in] mem_ctx   The memory context for the result
 * @param[in] ev        The tevent_context to run on
 * @param[in] stream    The stream to send data through
 * @param[in] queue     The existing send queue
 * @param[in] next_vector_fn    The next vector function
 * @param[in] next_vector_private       The private_data of the next vector function
 * @retval              The async request handle
 *
 * This function queues a blob for sending to destination through an existing
 * dgram socket. The async callback is triggered when the whole blob is
 * delivered to the underlying system socket.
 *
 * The caller needs to make sure that all non-scalar input parameters hang
 * arround for the whole lifetime of the request.
 */
struct tevent_req *tstream_readv_pdu_queue_send(TALLOC_CTX *mem_ctx,
                                struct tevent_context *ev,
                                struct tstream_context *stream,
                                struct tevent_queue *queue,
                                tstream_readv_pdu_next_vector_t next_vector_fn,
                                void *next_vector_private)
{
        struct tevent_req *req;
        struct tstream_readv_pdu_queue_state *state;
        bool ok;

        req = tevent_req_create(mem_ctx, &state,
                                struct tstream_readv_pdu_queue_state);
        if (!req) {
                return NULL;
        }

        state->caller.ev                        = ev;
        state->caller.stream                    = stream;
        state->caller.next_vector_fn            = next_vector_fn;
        state->caller.next_vector_private       = next_vector_private;
        state->ret                              = -1;

        ok = tevent_queue_add(queue,
                              ev,
                              req,
                              tstream_readv_pdu_queue_trigger,
                              NULL);
        if (!ok) {
                tevent_req_nomem(NULL, req);
                goto post;
        }

        return req;

 post:
        return tevent_req_post(req, ev);
}

static void tstream_readv_pdu_queue_trigger(struct tevent_req *req,
                                         void *private_data)
{
        struct tstream_readv_pdu_queue_state *state = tevent_req_data(req,
                                        struct tstream_readv_pdu_queue_state);
        struct tevent_req *subreq;

        subreq = tstream_readv_pdu_send(state,
                                        state->caller.ev,
                                        state->caller.stream,
                                        state->caller.next_vector_fn,
                                        state->caller.next_vector_private);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, tstream_readv_pdu_queue_done ,req);
}

static void tstream_readv_pdu_queue_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(subreq,
                                 struct tevent_req);
        struct tstream_readv_pdu_queue_state *state = tevent_req_data(req,
                                        struct tstream_readv_pdu_queue_state);
        int ret;
        int sys_errno;

        ret = tstream_readv_pdu_recv(subreq, &sys_errno);
        talloc_free(subreq);
        if (ret == -1) {
                tevent_req_error(req, sys_errno);
                return;
        }
        state->ret = ret;

        tevent_req_done(req);
}

int tstream_readv_pdu_queue_recv(struct tevent_req *req, int *perrno)
{
        struct tstream_readv_pdu_queue_state *state = tevent_req_data(req,
                                        struct tstream_readv_pdu_queue_state);
        int ret;

        ret = tsocket_simple_int_recv(req, perrno);
        if (ret == 0) {
                ret = state->ret;
        }

        tevent_req_received(req);
        return ret;
}

struct tstream_writev_queue_state {
        /* this structs are owned by the caller */
        struct {
                struct tevent_context *ev;
                struct tstream_context *stream;
                const struct iovec *vector;
                size_t count;
        } caller;
        int ret;
};

static void tstream_writev_queue_trigger(struct tevent_req *req,
                                         void *private_data);
static void tstream_writev_queue_done(struct tevent_req *subreq);

/**
 * @brief Queue a dgram blob for sending through the socket
 * @param[in] mem_ctx   The memory context for the result
 * @param[in] ev        The tevent_context to run on
 * @param[in] stream    The stream to send data through
 * @param[in] queue     The existing send queue
 * @param[in] vector    The iovec vector so write
 * @param[in] count     The size of the vector
 * @retval              The async request handle
 *
 * This function queues a blob for sending to destination through an existing
 * dgram socket. The async callback is triggered when the whole blob is
 * delivered to the underlying system socket.
 *
 * The caller needs to make sure that all non-scalar input parameters hang
 * arround for the whole lifetime of the request.
 */
struct tevent_req *tstream_writev_queue_send(TALLOC_CTX *mem_ctx,
                                             struct tevent_context *ev,
                                             struct tstream_context *stream,
                                             struct tevent_queue *queue,
                                             const struct iovec *vector,
                                             size_t count)
{
        struct tevent_req *req;
        struct tstream_writev_queue_state *state;
        bool ok;

        req = tevent_req_create(mem_ctx, &state,
                                struct tstream_writev_queue_state);
        if (!req) {
                return NULL;
        }

        state->caller.ev        = ev;
        state->caller.stream    = stream;
        state->caller.vector    = vector;
        state->caller.count     = count;
        state->ret              = -1;

        ok = tevent_queue_add(queue,
                              ev,
                              req,
                              tstream_writev_queue_trigger,
                              NULL);
        if (!ok) {
                tevent_req_nomem(NULL, req);
                goto post;
        }

        return req;

 post:
        return tevent_req_post(req, ev);
}

static void tstream_writev_queue_trigger(struct tevent_req *req,
                                         void *private_data)
{
        struct tstream_writev_queue_state *state = tevent_req_data(req,
                                        struct tstream_writev_queue_state);
        struct tevent_req *subreq;

        subreq = tstream_writev_send(state,
                                     state->caller.ev,
                                     state->caller.stream,
                                     state->caller.vector,
                                     state->caller.count);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, tstream_writev_queue_done ,req);
}

static void tstream_writev_queue_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(subreq,
                                 struct tevent_req);
        struct tstream_writev_queue_state *state = tevent_req_data(req,
                                        struct tstream_writev_queue_state);
        int ret;
        int sys_errno;

        ret = tstream_writev_recv(subreq, &sys_errno);
        talloc_free(subreq);
        if (ret == -1) {
                tevent_req_error(req, sys_errno);
                return;
        }
        state->ret = ret;

        tevent_req_done(req);
}

int tstream_writev_queue_recv(struct tevent_req *req, int *perrno)
{
        struct tstream_writev_queue_state *state = tevent_req_data(req,
                                        struct tstream_writev_queue_state);
        int ret;

        ret = tsocket_simple_int_recv(req, perrno);
        if (ret == 0) {
                ret = state->ret;
        }

        tevent_req_received(req);
        return ret;
}