| 1 | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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| 2 | /* ***** BEGIN LICENSE BLOCK *****
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| 3 | * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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| 4 | *
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| 5 | * The contents of this file are subject to the Mozilla Public License Version
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| 6 | * 1.1 (the "License"); you may not use this file except in compliance with
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| 7 | * the License. You may obtain a copy of the License at
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| 8 | * http://www.mozilla.org/MPL/
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| 9 | *
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| 10 | * Software distributed under the License is distributed on an "AS IS" basis,
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| 11 | * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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| 12 | * for the specific language governing rights and limitations under the
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| 13 | * License.
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| 14 | *
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| 15 | * The Original Code is mozilla.org code.
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| 16 | *
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| 17 | * The Initial Developer of the Original Code is
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| 18 | * Netscape Communications Corporation.
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| 19 | * Portions created by the Initial Developer are Copyright (C) 1998
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| 20 | * the Initial Developer. All Rights Reserved.
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| 21 | *
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| 22 | * Contributor(s):
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| 23 | *
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| 24 | * Alternatively, the contents of this file may be used under the terms of
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| 25 | * either of the GNU General Public License Version 2 or later (the "GPL"),
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| 26 | * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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| 27 | * in which case the provisions of the GPL or the LGPL are applicable instead
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| 28 | * of those above. If you wish to allow use of your version of this file only
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| 29 | * under the terms of either the GPL or the LGPL, and not to allow others to
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| 30 | * use your version of this file under the terms of the MPL, indicate your
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| 31 | * decision by deleting the provisions above and replace them with the notice
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| 32 | * and other provisions required by the GPL or the LGPL. If you do not delete
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| 33 | * the provisions above, a recipient may use your version of this file under
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| 34 | * the terms of any one of the MPL, the GPL or the LGPL.
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| 35 | *
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| 36 | * ***** END LICENSE BLOCK ***** */
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| 37 |
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| 38 | #include "nsAutoLock.h"
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| 39 |
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| 40 | #ifdef DEBUG
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| 41 |
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| 42 | #include "plhash.h"
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| 43 | #include "prprf.h"
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| 44 | #include "prlock.h"
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| 45 | #include "prthread.h"
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| 46 | #include "nsDebug.h"
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| 47 | #include "nsVoidArray.h"
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| 48 |
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| 49 | #ifdef NS_TRACE_MALLOC_XXX
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| 50 | # include <stdio.h>
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| 51 | # include "nsTraceMalloc.h"
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| 52 | #endif
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| 53 |
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| 54 | static PRUintn LockStackTPI = (PRUintn)-1;
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| 55 | static PLHashTable* OrderTable = 0;
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| 56 | static PRLock* OrderTableLock = 0;
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| 57 |
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| 58 | static const char* const LockTypeNames[] = {"Lock", "Monitor", "CMonitor"};
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| 59 |
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| 60 | struct nsNamedVector : public nsVoidArray {
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| 61 | const char* mName;
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| 62 |
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| 63 | #ifdef NS_TRACE_MALLOC_XXX
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| 64 | // Callsites for the inner locks/monitors stored in our base nsVoidArray.
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| 65 | // This array parallels our base nsVoidArray.
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| 66 | nsVoidArray mInnerSites;
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| 67 | #endif
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| 68 |
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| 69 | nsNamedVector(const char* name = 0, PRUint32 initialSize = 0)
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| 70 | : nsVoidArray(initialSize),
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| 71 | mName(name)
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| 72 | {
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| 73 | }
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| 74 | };
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| 75 |
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| 76 | static void * PR_CALLBACK
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| 77 | _hash_alloc_table(void *pool, PRSize size)
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| 78 | {
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| 79 | return operator new(size);
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| 80 | }
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| 81 |
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| 82 | static void PR_CALLBACK
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| 83 | _hash_free_table(void *pool, void *item)
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| 84 | {
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| 85 | operator delete(item);
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| 86 | }
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| 87 |
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| 88 | static PLHashEntry * PR_CALLBACK
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| 89 | _hash_alloc_entry(void *pool, const void *key)
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| 90 | {
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| 91 | return new PLHashEntry;
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| 92 | }
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| 93 |
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| 94 | /*
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| 95 | * Because monitors and locks may be associated with an nsAutoLockBase,
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| 96 | * without having had their associated nsNamedVector created explicitly in
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| 97 | * nsAutoMonitor::NewMonitor/DeleteMonitor, we need to provide a freeEntry
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| 98 | * PLHashTable hook, to avoid leaking nsNamedVectors which are replaced by
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| 99 | * nsAutoMonitor::NewMonitor.
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| 100 | *
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| 101 | * There is still a problem with the OrderTable containing orphaned
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| 102 | * nsNamedVector entries, for manually created locks wrapped by nsAutoLocks.
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| 103 | * (there should be no manually created monitors wrapped by nsAutoMonitors:
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| 104 | * you should use nsAutoMonitor::NewMonitor and nsAutoMonitor::DestroyMonitor
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| 105 | * instead of PR_NewMonitor and PR_DestroyMonitor). These lock vectors don't
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| 106 | * strictly leak, as they are killed on shutdown, but there are unnecessary
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| 107 | * named vectors in the hash table that outlive their associated locks.
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| 108 | *
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| 109 | * XXX so we should have nsLock, nsMonitor, etc. and strongly type their
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| 110 | * XXX nsAutoXXX counterparts to take only the non-auto types as inputs
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| 111 | */
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| 112 | static void PR_CALLBACK
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| 113 | _hash_free_entry(void *pool, PLHashEntry *entry, PRUintn flag)
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| 114 | {
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| 115 | nsNamedVector* vec = (nsNamedVector*) entry->value;
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| 116 | if (vec) {
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| 117 | entry->value = 0;
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| 118 | delete vec;
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| 119 | }
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| 120 | if (flag == HT_FREE_ENTRY)
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| 121 | delete entry;
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| 122 | }
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| 123 |
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| 124 | static const PLHashAllocOps _hash_alloc_ops = {
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| 125 | _hash_alloc_table, _hash_free_table,
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| 126 | _hash_alloc_entry, _hash_free_entry
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| 127 | };
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| 128 |
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| 129 | PR_STATIC_CALLBACK(PRIntn)
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| 130 | _purge_one(PLHashEntry* he, PRIntn cnt, void* arg)
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| 131 | {
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| 132 | nsNamedVector* vec = (nsNamedVector*) he->value;
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| 133 |
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| 134 | if (he->key == arg)
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| 135 | return HT_ENUMERATE_REMOVE;
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| 136 | vec->RemoveElement(arg);
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| 137 | return HT_ENUMERATE_NEXT;
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| 138 | }
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| 139 |
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| 140 | PR_STATIC_CALLBACK(void)
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| 141 | OnMonitorRecycle(void* addr)
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| 142 | {
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| 143 | PR_Lock(OrderTableLock);
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| 144 | PL_HashTableEnumerateEntries(OrderTable, _purge_one, addr);
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| 145 | PR_Unlock(OrderTableLock);
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| 146 | }
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| 147 |
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| 148 | PR_STATIC_CALLBACK(PLHashNumber)
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| 149 | _hash_pointer(const void* key)
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| 150 | {
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| 151 | return PLHashNumber(NS_PTR_TO_INT32(key)) >> 2;
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| 152 | }
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| 153 |
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| 154 | // Must be single-threaded here, early in primordial thread.
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| 155 | static void InitAutoLockStatics()
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| 156 | {
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| 157 | (void) PR_NewThreadPrivateIndex(&LockStackTPI, 0);
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| 158 | OrderTable = PL_NewHashTable(64, _hash_pointer,
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| 159 | PL_CompareValues, PL_CompareValues,
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| 160 | &_hash_alloc_ops, 0);
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| 161 | if (OrderTable && !(OrderTableLock = PR_NewLock())) {
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| 162 | PL_HashTableDestroy(OrderTable);
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| 163 | OrderTable = 0;
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| 164 | }
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| 165 | }
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| 166 |
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| 167 | void _FreeAutoLockStatics()
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| 168 | {
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| 169 | PLHashTable* table = OrderTable;
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| 170 | if (!table) return;
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| 171 |
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| 172 | // Called at shutdown, so we don't need to lock.
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| 173 | PR_DestroyLock(OrderTableLock);
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| 174 | OrderTableLock = 0;
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| 175 | PL_HashTableDestroy(table);
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| 176 | OrderTable = 0;
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| 177 | }
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| 178 |
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| 179 | static nsNamedVector* GetVector(PLHashTable* table, const void* key)
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| 180 | {
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| 181 | PLHashNumber hash = _hash_pointer(key);
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| 182 | PLHashEntry** hep = PL_HashTableRawLookup(table, hash, key);
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| 183 | PLHashEntry* he = *hep;
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| 184 | if (he)
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| 185 | return (nsNamedVector*) he->value;
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| 186 | nsNamedVector* vec = new nsNamedVector();
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| 187 | if (vec)
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| 188 | PL_HashTableRawAdd(table, hep, hash, key, vec);
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| 189 | return vec;
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| 190 | }
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| 191 |
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| 192 | // We maintain an acyclic graph in OrderTable, so recursion can't diverge.
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| 193 | static PRBool Reachable(PLHashTable* table, const void* goal, const void* start)
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| 194 | {
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| 195 | PR_ASSERT(goal);
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| 196 | PR_ASSERT(start);
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| 197 | nsNamedVector* vec = GetVector(table, start);
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| 198 | for (PRUint32 i = 0, n = vec->Count(); i < n; i++) {
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| 199 | void* addr = vec->ElementAt(i);
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| 200 | if (addr == goal || Reachable(table, goal, addr))
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| 201 | return PR_TRUE;
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| 202 | }
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| 203 | return PR_FALSE;
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| 204 | }
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| 205 |
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| 206 | static PRBool WellOrdered(const void* addr1, const void* addr2,
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| 207 | const void *callsite2, PRUint32* index2p,
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| 208 | nsNamedVector** vec1p, nsNamedVector** vec2p)
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| 209 | {
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| 210 | PRBool rv = PR_TRUE;
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| 211 | PLHashTable* table = OrderTable;
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| 212 | if (!table) return rv;
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| 213 | PR_Lock(OrderTableLock);
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| 214 |
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| 215 | // Check whether we've already asserted (addr1 < addr2).
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| 216 | nsNamedVector* vec1 = GetVector(table, addr1);
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| 217 | if (vec1) {
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| 218 | PRUint32 i, n;
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| 219 |
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| 220 | for (i = 0, n = vec1->Count(); i < n; i++)
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| 221 | if (vec1->ElementAt(i) == addr2)
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| 222 | break;
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| 223 |
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| 224 | if (i == n) {
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| 225 | // Now check for (addr2 < addr1) and return false if so.
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| 226 | nsNamedVector* vec2 = GetVector(table, addr2);
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| 227 | if (vec2) {
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| 228 | for (i = 0, n = vec2->Count(); i < n; i++) {
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| 229 | void* addri = vec2->ElementAt(i);
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| 230 | PR_ASSERT(addri);
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| 231 | if (addri == addr1 || Reachable(table, addr1, addri)) {
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| 232 | *index2p = i;
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| 233 | *vec1p = vec1;
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| 234 | *vec2p = vec2;
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| 235 | rv = PR_FALSE;
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| 236 | break;
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| 237 | }
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| 238 | }
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| 239 |
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| 240 | if (rv) {
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| 241 | // Assert (addr1 < addr2) into the order table.
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| 242 | // XXX fix plvector/nsVector to use const void*
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| 243 | vec1->AppendElement((void*) addr2);
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| 244 | #ifdef NS_TRACE_MALLOC_XXX
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| 245 | vec1->mInnerSites.AppendElement((void*) callsite2);
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| 246 | #endif
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| 247 | }
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| 248 | }
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| 249 | }
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| 250 | }
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| 251 |
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| 252 | PR_Unlock(OrderTableLock);
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| 253 | return rv;
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| 254 | }
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| 255 |
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| 256 | nsAutoLockBase::nsAutoLockBase(void* addr, nsAutoLockType type)
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| 257 | {
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| 258 | if (LockStackTPI == PRUintn(-1))
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| 259 | InitAutoLockStatics();
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| 260 |
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| 261 | nsAutoLockBase* stackTop =
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| 262 | (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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| 263 | if (stackTop) {
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| 264 | if (stackTop->mAddr == addr) {
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| 265 | // Ignore reentry: it's legal for monitors, and NSPR will assert
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| 266 | // if you reenter a PRLock.
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| 267 | } else if (!addr) {
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| 268 | // Ignore null addresses: the caller promises not to use the
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| 269 | // lock at all, and NSPR will assert if you enter it.
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| 270 | } else {
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| 271 | const void* node =
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| 272 | #ifdef NS_TRACE_MALLOC_XXX
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| 273 | NS_GetStackTrace(1)
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| 274 | #else
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| 275 | nsnull
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| 276 | #endif
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| 277 | ;
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| 278 | nsNamedVector* vec1;
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| 279 | nsNamedVector* vec2;
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| 280 | PRUint32 i2;
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| 281 |
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| 282 | if (!WellOrdered(stackTop->mAddr, addr, node, &i2, &vec1, &vec2)) {
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| 283 | char buf[128];
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| 284 | PR_snprintf(buf, sizeof buf,
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| 285 | "Potential deadlock between %s%s@%p and %s%s@%p",
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| 286 | vec1->mName ? vec1->mName : "",
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| 287 | LockTypeNames[stackTop->mType],
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| 288 | stackTop->mAddr,
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| 289 | vec2->mName ? vec2->mName : "",
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| 290 | LockTypeNames[type],
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| 291 | addr);
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| 292 | #ifdef NS_TRACE_MALLOC_XXX
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| 293 | fprintf(stderr, "\n*** %s\n\nCurrent stack:\n", buf);
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| 294 | NS_DumpStackTrace(node, stderr);
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| 295 |
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| 296 | fputs("\nPrevious stack:\n", stderr);
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| 297 | NS_DumpStackTrace(vec2->mInnerSites.ElementAt(i2), stderr);
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| 298 | putc('\n', stderr);
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| 299 | #endif
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| 300 | NS_ERROR(buf);
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| 301 | }
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| 302 | }
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| 303 | }
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| 304 |
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| 305 | mAddr = addr;
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| 306 | mDown = stackTop;
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| 307 | mType = type;
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| 308 | if (mAddr)
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| 309 | (void) PR_SetThreadPrivate(LockStackTPI, this);
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| 310 | }
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| 311 |
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| 312 | nsAutoLockBase::~nsAutoLockBase()
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| 313 | {
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| 314 | if (mAddr)
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| 315 | (void) PR_SetThreadPrivate(LockStackTPI, mDown);
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| 316 | }
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| 317 |
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| 318 | void nsAutoLockBase::Show()
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| 319 | {
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| 320 | if (!mAddr)
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| 321 | return;
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| 322 | nsAutoLockBase* curr = (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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| 323 | nsAutoLockBase* prev = nsnull;
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| 324 | while (curr != mDown) {
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| 325 | prev = curr;
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| 326 | curr = prev->mDown;
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| 327 | }
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| 328 | if (!prev)
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| 329 | PR_SetThreadPrivate(LockStackTPI, this);
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| 330 | else
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| 331 | prev->mDown = this;
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| 332 | }
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| 333 |
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| 334 | void nsAutoLockBase::Hide()
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| 335 | {
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| 336 | if (!mAddr)
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| 337 | return;
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| 338 | nsAutoLockBase* curr = (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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| 339 | nsAutoLockBase* prev = nsnull;
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| 340 | while (curr != this) {
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| 341 | prev = curr;
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| 342 | curr = prev->mDown;
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| 343 | }
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| 344 | if (!prev)
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| 345 | PR_SetThreadPrivate(LockStackTPI, mDown);
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| 346 | else
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| 347 | prev->mDown = mDown;
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| 348 | }
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| 349 |
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| 350 | #endif /* DEBUG */
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| 351 |
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| 352 | PRMonitor* nsAutoMonitor::NewMonitor(const char* name)
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| 353 | {
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| 354 | PRMonitor* mon = PR_NewMonitor();
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| 355 | #ifdef DEBUG
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| 356 | if (mon && OrderTable) {
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| 357 | nsNamedVector* value = new nsNamedVector(name);
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| 358 | if (value) {
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| 359 | PR_Lock(OrderTableLock);
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| 360 | PL_HashTableAdd(OrderTable, mon, value);
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| 361 | PR_Unlock(OrderTableLock);
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| 362 | }
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| 363 | }
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| 364 | #endif
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| 365 | return mon;
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| 366 | }
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| 367 |
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| 368 | void nsAutoMonitor::DestroyMonitor(PRMonitor* mon)
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| 369 | {
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| 370 | #ifdef DEBUG
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| 371 | if (OrderTable)
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| 372 | OnMonitorRecycle(mon);
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| 373 | #endif
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| 374 | PR_DestroyMonitor(mon);
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| 375 | }
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| 376 |
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| 377 | void nsAutoMonitor::Enter()
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| 378 | {
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| 379 | #ifdef DEBUG
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| 380 | if (!mAddr) {
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| 381 | NS_ERROR("It is not legal to enter a null monitor");
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| 382 | return;
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| 383 | }
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| 384 | nsAutoLockBase* stackTop =
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| 385 | (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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| 386 | NS_ASSERTION(stackTop == mDown, "non-LIFO nsAutoMonitor::Enter");
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| 387 | mDown = stackTop;
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| 388 | (void) PR_SetThreadPrivate(LockStackTPI, this);
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| 389 | #endif
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| 390 | PR_EnterMonitor(mMonitor);
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| 391 | mLockCount += 1;
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| 392 | }
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| 393 |
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| 394 | void nsAutoMonitor::Exit()
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| 395 | {
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| 396 | #ifdef DEBUG
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| 397 | if (!mAddr) {
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| 398 | NS_ERROR("It is not legal to exit a null monitor");
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| 399 | return;
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| 400 | }
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| 401 | (void) PR_SetThreadPrivate(LockStackTPI, mDown);
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| 402 | #endif
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| 403 | PRStatus status = PR_ExitMonitor(mMonitor);
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| 404 | NS_ASSERTION(status == PR_SUCCESS, "PR_ExitMonitor failed");
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| 405 | mLockCount -= 1;
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| 406 | }
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| 407 |
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