mono/metadata/monitor.h

   1 /**
   2  * \file
   3  * Monitor locking functions
   4  *
   5  * Author:
   6  *      Dick Porter (dick@ximian.com)
   7  *
   8  * (C) 2003 Ximian, Inc
   9  */
  10
  11 #ifndef _MONO_METADATA_MONITOR_H_
  12 #define _MONO_METADATA_MONITOR_H_
  13
  14 #include <glib.h>
  15 #include <mono/metadata/object.h>
  16 #include <mono/utils/mono-compiler.h>
  17 #include <mono/utils/mono-coop-mutex.h>
  18 #include <mono/metadata/icalls.h>
  19
  20 #define OWNER_MASK              0x0000ffff
  21 #define ENTRY_COUNT_MASK        0xffff0000
  22 #define ENTRY_COUNT_WAITERS     0x80000000
  23 #define ENTRY_COUNT_ZERO        0x7fff0000
  24 #define ENTRY_COUNT_SHIFT       16
  25
  26 struct _MonoThreadsSync
  27 {
  28         /*
  29          * The entry count field can be negative, which would mean that the entry_sem is
  30          * signaled and nobody is waiting to acquire it. This can happen when the thread
  31          * that was waiting is either interrupted or timeouts, and the owner releases
  32          * the lock before the forementioned thread updates the entry count.
  33          *
  34          * The 0 entry_count value is encoded as ENTRY_COUNT_ZERO, positive numbers being
  35          * greater than it and negative numbers smaller than it.
  36          */
  37         guint32 status;                 /* entry_count (16) | owner_id (16) */
  38         guint32 nest;
  39 #ifdef HAVE_MOVING_COLLECTOR
  40         gint32 hash_code;
  41 #endif
  42         GSList *wait_list;
  43         void *data;
  44         MonoCoopMutex *entry_mutex;
  45         MonoCoopCond *entry_cond;
  46 };
  47
  48 /*
  49  * Lock word format:
  50  *
  51  * The least significant bit stores whether a hash for the object is computed
  52  * which is stored either in the lock word or in the MonoThreadsSync structure
  53  * that the lock word points to.
  54  *
  55  * The second bit stores whether the lock word is inflated, containing an
  56  * address to the MonoThreadsSync structure.
  57  *
  58  * If both bits are 0, either the lock word is free (entire lock word is 0)
  59  * or it is a thin/flat lock.
  60  *
  61  * 32-bit
  62  *            LOCK_WORD_FLAT:    [owner:22 | nest:8 | status:2]
  63  *       LOCK_WORD_THIN_HASH:    [hash:30 | status:2]
  64  *        LOCK_WORD_INFLATED:    [sync:30 | status:2]
  65  *        LOCK_WORD_FAT_HASH:    [sync:30 | status:2]
  66  *
  67  * 64-bit
  68  *            LOCK_WORD_FLAT:    [unused:22 | owner:32 | nest:8 | status:2]
  69  *       LOCK_WORD_THIN_HASH:    [hash:62 | status:2]
  70  *        LOCK_WORD_INFLATED:    [sync:62 | status:2]
  71  *        LOCK_WORD_FAT_HASH:    [sync:62 | status:2]
  72  *
  73  * In order to save processing time and to have one additional value, the nest
  74  * count starts from 0 for the lock word (just valid thread ID in the lock word
  75  * means that the thread holds the lock once, although nest is 0).
  76  * FIXME Have the same convention on inflated locks
  77  */
  78
  79 typedef union {
  80         gsize lock_word;
  81         MonoThreadsSync *sync;
  82 } LockWord;
  83
  84 enum {
  85         LOCK_WORD_FLAT = 0,
  86         LOCK_WORD_HAS_HASH = 1,
  87         LOCK_WORD_INFLATED = 2,
  88
  89         LOCK_WORD_STATUS_BITS = 2,
  90         LOCK_WORD_NEST_BITS = 8,
  91
  92         LOCK_WORD_STATUS_MASK = (1 << LOCK_WORD_STATUS_BITS) - 1,
  93         LOCK_WORD_NEST_MASK = ((1 << LOCK_WORD_NEST_BITS) - 1) << LOCK_WORD_STATUS_BITS,
  94
  95         LOCK_WORD_HASH_SHIFT = LOCK_WORD_STATUS_BITS,
  96         LOCK_WORD_NEST_SHIFT = LOCK_WORD_STATUS_BITS,
  97         LOCK_WORD_OWNER_SHIFT = LOCK_WORD_STATUS_BITS + LOCK_WORD_NEST_BITS
  98 };
  99
 100 MONO_API void
 101 mono_locks_dump (gboolean include_untaken);
 102
 103 void
 104 mono_monitor_init (void);
 105
 106 void
 107 mono_monitor_cleanup (void);
 108
 109 ICALL_EXTERN_C
 110 MonoBoolean
 111 mono_monitor_enter_internal (MonoObject *obj);
 112
 113 ICALL_EXTERN_C
 114 void
 115 mono_monitor_enter_v4_internal (MonoObject *obj, MonoBoolean *lock_taken);
 116
 117 ICALL_EXTERN_C
 118 guint32
 119 mono_monitor_enter_fast (MonoObject *obj);
 120
 121 ICALL_EXTERN_C
 122 guint32
 123 mono_monitor_enter_v4_fast (MonoObject *obj, MonoBoolean *lock_taken);
 124
 125 guint32
 126 mono_monitor_get_object_monitor_gchandle (MonoObject *object);
 127
 128 void
 129 mono_monitor_threads_sync_members_offset (int *status_offset, int *nest_offset);
 130 #define MONO_THREADS_SYNC_MEMBER_OFFSET(o)      ((o)>>8)
 131 #define MONO_THREADS_SYNC_MEMBER_SIZE(o)        ((o)&0xff)
 132
 133 #if ENABLE_NETCORE
 134 ICALL_EXPORT
 135 gint64
 136 ves_icall_System_Threading_Monitor_Monitor_LockContentionCount (void);
 137 #endif
 138
 139 #endif /* _MONO_METADATA_MONITOR_H_ */