diff options
Diffstat (limited to 'generic/tclThreadAlloc.c')
| -rwxr-xr-x | generic/tclThreadAlloc.c | 194 |
1 files changed, 98 insertions, 96 deletions
diff --git a/generic/tclThreadAlloc.c b/generic/tclThreadAlloc.c index c03cc9e..f36d0d7 100755 --- a/generic/tclThreadAlloc.c +++ b/generic/tclThreadAlloc.c @@ -2,24 +2,24 @@ * tclThreadAlloc.c -- * * This is a very fast storage allocator for used with threads (designed - * avoid lock contention). The basic strategy is to allocate memory in + * avoid lock contention). The basic strategy is to allocate memory in * fixed size blocks from block caches. * * The Initial Developer of the Original Code is America Online, Inc. * Portions created by AOL are Copyright (C) 1999 America Online, Inc. * - * See the file "license.terms" for information on usage and redistribution - * of this file, and for a DISCLAIMER OF ALL WARRANTIES. + * See the file "license.terms" for information on usage and redistribution of + * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tclThreadAlloc.c,v 1.16 2005/05/10 18:34:50 kennykb Exp $ + * RCS: @(#) $Id: tclThreadAlloc.c,v 1.17 2005/07/24 22:56:44 dkf Exp $ */ #include "tclInt.h" #if defined(TCL_THREADS) && defined(USE_THREAD_ALLOC) /* - * If range checking is enabled, an additional byte will be allocated - * to store the magic number at the end of the requested memory. + * If range checking is enabled, an additional byte will be allocated to store + * the magic number at the end of the requested memory. */ #ifndef RCHECK @@ -31,33 +31,32 @@ #endif /* - * The following define the number of Tcl_Obj's to allocate/move - * at a time and the high water mark to prune a per-thread cache. - * On a 32 bit system, sizeof(Tcl_Obj) = 24 so 800 * 24 = ~16k. + * The following define the number of Tcl_Obj's to allocate/move at a time and + * the high water mark to prune a per-thread cache. On a 32 bit system, + * sizeof(Tcl_Obj) = 24 so 800 * 24 = ~16k. */ -#define NOBJALLOC 800 +#define NOBJALLOC 800 #define NOBJHIGH 1200 /* - * The following defines the number of buckets in the bucket - * cache and those block sizes from (1<<4) to (1<<(3+NBUCKETS)) + * The following defines the number of buckets in the bucket cache and those + * block sizes from (1<<4) to (1<<(3+NBUCKETS)) */ -#define NBUCKETS 11 -#define MAXALLOC 16284 +#define NBUCKETS 11 +#define MAXALLOC 16284 /* - * The following union stores accounting information for - * each block including two small magic numbers and - * a bucket number when in use or a next pointer when - * free. The original requested size (not including - * the Block overhead) is also maintained. + * The following union stores accounting information for each block including + * two small magic numbers and a bucket number when in use or a next pointer + * when free. The original requested size (not including the Block overhead) + * is also maintained. */ typedef struct Block { union { - struct Block *next; /* Next in free list. */ + struct Block *next; /* Next in free list. */ struct { unsigned char magic1; /* First magic number. */ unsigned char bucket; /* Bucket block allocated from. */ @@ -65,7 +64,7 @@ typedef struct Block { unsigned char magic2; /* Second magic number. */ } s; } u; - size_t reqSize; /* Requested allocation size. */ + size_t reqSize; /* Requested allocation size. */ } Block; #define nextBlock u.next #define sourceBucket u.s.bucket @@ -74,48 +73,47 @@ typedef struct Block { #define MAGIC 0xEF /* - * The following structure defines a bucket of blocks with - * various accounting and statistics information. + * The following structure defines a bucket of blocks with various accounting + * and statistics information. */ typedef struct Bucket { - Block *firstPtr; /* First block available */ - int numFree; /* Number of blocks available */ + Block *firstPtr; /* First block available */ + int numFree; /* Number of blocks available */ /* All fields below for accounting only */ - int numRemoves; /* Number of removes from bucket */ - int numInserts; /* Number of inserts into bucket */ - int numWaits; /* Number of waits to acquire a lock */ - int numLocks; /* Number of locks acquired */ - int totalAssigned; /* Total space assigned to bucket */ + int numRemoves; /* Number of removes from bucket */ + int numInserts; /* Number of inserts into bucket */ + int numWaits; /* Number of waits to acquire a lock */ + int numLocks; /* Number of locks acquired */ + int totalAssigned; /* Total space assigned to bucket */ } Bucket; /* - * The following structure defines a cache of buckets and objs, of - * which there will be (at most) one per thread. + * The following structure defines a cache of buckets and objs, of which there + * will be (at most) one per thread. */ typedef struct Cache { - struct Cache *nextPtr; /* Linked list of cache entries */ - Tcl_ThreadId owner; /* Which thread's cache is this? */ - Tcl_Obj *firstObjPtr; /* List of free objects for thread */ - int numObjects; /* Number of objects for thread */ - int totalAssigned; /* Total space assigned to thread */ - Bucket buckets[NBUCKETS]; /* The buckets for this thread */ + struct Cache *nextPtr; /* Linked list of cache entries */ + Tcl_ThreadId owner; /* Which thread's cache is this? */ + Tcl_Obj *firstObjPtr; /* List of free objects for thread */ + int numObjects; /* Number of objects for thread */ + int totalAssigned; /* Total space assigned to thread */ + Bucket buckets[NBUCKETS]; /* The buckets for this thread */ } Cache; /* - * The following array specifies various per-bucket limits and locks. - * The values are statically initialized to avoid calculating them - * repeatedly. + * The following array specifies various per-bucket limits and locks. The + * values are statically initialized to avoid calculating them repeatedly. */ static struct { - size_t blockSize; /* Bucket blocksize. */ - int maxBlocks; /* Max blocks before move to share. */ - int numMove; /* Num blocks to move to share. */ - Tcl_Mutex *lockPtr; /* Share bucket lock. */ + size_t blockSize; /* Bucket blocksize. */ + int maxBlocks; /* Max blocks before move to share. */ + int numMove; /* Num blocks to move to share. */ + Tcl_Mutex *lockPtr; /* Share bucket lock. */ } bucketInfo[NBUCKETS] = { { 16, 1024, 512, NULL}, { 32, 512, 256, NULL}, @@ -146,8 +144,7 @@ static void MoveObjs _ANSI_ARGS_((Cache *fromPtr, Cache *toPtr, int numMove)); /* - * Local variables defined in this file and initialized at - * startup. + * Local variables defined in this file and initialized at startup. */ static Tcl_Mutex *listLockPtr; @@ -306,10 +303,9 @@ TclpAlloc(reqSize) } /* - * Increment the requested size to include room for - * the Block structure. Call malloc() directly if the - * required amount is greater than the largest block, - * otherwise pop the smallest block large enough, + * Increment the requested size to include room for the Block structure. + * Call malloc() directly if the required amount is greater than the + * largest block, otherwise pop the smallest block large enough, * allocating more blocks if necessary. */ @@ -377,10 +373,9 @@ TclpFree(ptr) } /* - * Get the block back from the user pointer and call system free - * directly for large blocks. Otherwise, push the block back on - * the bucket and move blocks to the shared cache if there are now - * too many free. + * Get the block back from the user pointer and call system free directly + * for large blocks. Otherwise, push the block back on the bucket and move + * blocks to the shared cache if there are now too many free. */ blockPtr = Ptr2Block(ptr); @@ -390,11 +385,13 @@ TclpFree(ptr) free(blockPtr); return; } + cachePtr->buckets[bucket].totalAssigned -= blockPtr->reqSize; blockPtr->nextBlock = cachePtr->buckets[bucket].firstPtr; cachePtr->buckets[bucket].firstPtr = blockPtr; ++cachePtr->buckets[bucket].numFree; ++cachePtr->buckets[bucket].numInserts; + if (cachePtr != sharedPtr && cachePtr->buckets[bucket].numFree > bucketInfo[bucket].maxBlocks) { PutBlocks(cachePtr, bucket, bucketInfo[bucket].numMove); @@ -437,10 +434,9 @@ TclpRealloc(ptr, reqSize) } /* - * If the block is not a system block and fits in place, - * simply return the existing pointer. Otherwise, if the block - * is a system block and the new size would also require a system - * block, call realloc() directly. + * If the block is not a system block and fits in place, simply return the + * existing pointer. Otherwise, if the block is a system block and the new + * size would also require a system block, call realloc() directly. */ blockPtr = Ptr2Block(ptr); @@ -496,8 +492,8 @@ TclpRealloc(ptr, reqSize) * Pointer to uninitialized Tcl_Obj. * * Side effects: - * May move Tcl_Obj's from shared cached or allocate new Tcl_Obj's - * if list is empty. + * May move Tcl_Obj's from shared cached or allocate new Tcl_Obj's if + * list is empty. * *---------------------------------------------------------------------- */ @@ -506,20 +502,20 @@ Tcl_Obj * TclThreadAllocObj(void) { register Cache *cachePtr = TclpGetAllocCache(); - register int numMove; register Tcl_Obj *objPtr; - Tcl_Obj *newObjsPtr; if (cachePtr == NULL) { cachePtr = GetCache(); } /* - * Get this thread's obj list structure and move - * or allocate new objs if necessary. + * Get this thread's obj list structure and move or allocate new objs if + * necessary. */ if (cachePtr->numObjects == 0) { + register int numMove; + Tcl_MutexLock(objLockPtr); numMove = sharedPtr->numObjects; if (numMove > 0) { @@ -530,6 +526,8 @@ TclThreadAllocObj(void) } Tcl_MutexUnlock(objLockPtr); if (cachePtr->numObjects == 0) { + Tcl_Obj *newObjsPtr; + cachePtr->numObjects = numMove = NOBJALLOC; newObjsPtr = malloc(sizeof(Tcl_Obj) * numMove); if (newObjsPtr == NULL) { @@ -564,8 +562,7 @@ TclThreadAllocObj(void) * None. * * Side effects: - * May move free Tcl_Obj's to shared list upon hitting high - * water mark. + * May move free Tcl_Obj's to shared list upon hitting high water mark. * *---------------------------------------------------------------------- */ @@ -589,8 +586,8 @@ TclThreadFreeObj(objPtr) ++cachePtr->numObjects; /* - * If the number of free objects has exceeded the high - * water mark, move some blocks to the shared list. + * If the number of free objects has exceeded the high water mark, move + * some blocks to the shared list. */ if (cachePtr->numObjects > NOBJHIGH) { @@ -679,9 +676,8 @@ MoveObjs(fromPtr, toPtr, numMove) fromPtr->numObjects -= numMove; /* - * Find the last object to be moved; set the next one - * (the first one not to be moved) as the first object - * in the 'from' cache. + * Find the last object to be moved; set the next one (the first one not + * to be moved) as the first object in the 'from' cache. */ while (--numMove) { @@ -690,8 +686,8 @@ MoveObjs(fromPtr, toPtr, numMove) fromPtr->firstObjPtr = objPtr->internalRep.otherValuePtr; /* - * Move all objects as a block - they are already linked to - * each other, we just have to update the first and last. + * Move all objects as a block - they are already linked to each other, we + * just have to update the first and last. */ objPtr->internalRep.otherValuePtr = toPtr->firstObjPtr; @@ -764,8 +760,8 @@ Ptr2Block(ptr) * None. * * Side effects: - * Lock activity and contention are monitored globally and on - * a per-cache basis. + * Lock activity and contention are monitored globally and on a per-cache + * basis. * *---------------------------------------------------------------------- */ @@ -821,8 +817,8 @@ PutBlocks(cachePtr, bucket, numMove) register int n = numMove; /* - * Before acquiring the lock, walk the block list to find - * the last block to be moved. + * Before acquiring the lock, walk the block list to find the last block + * to be moved. */ firstPtr = lastPtr = cachePtr->buckets[bucket].firstPtr; @@ -833,8 +829,8 @@ PutBlocks(cachePtr, bucket, numMove) cachePtr->buckets[bucket].numFree -= numMove; /* - * Aquire the lock and place the list of blocks at the front - * of the shared cache bucket. + * Aquire the lock and place the list of blocks at the front of the shared + * cache bucket. */ LockBucket(cachePtr, bucket); @@ -867,13 +863,12 @@ GetBlocks(cachePtr, bucket) { register Block *blockPtr; register int n; - register size_t size; /* - * First, atttempt to move blocks from the shared cache. Note - * the potentially dirty read of numFree before acquiring the lock - * which is a slight performance enhancement. The value is - * verified after the lock is actually acquired. + * First, atttempt to move blocks from the shared cache. Note the + * potentially dirty read of numFree before acquiring the lock which is a + * slight performance enhancement. The value is verified after the lock is + * actually acquired. */ if (cachePtr != sharedPtr && sharedPtr->buckets[bucket].numFree > 0) { @@ -881,8 +876,8 @@ GetBlocks(cachePtr, bucket) if (sharedPtr->buckets[bucket].numFree > 0) { /* - * Either move the entire list or walk the list to find - * the last block to move. + * Either move the entire list or walk the list to find the last + * block to move. */ n = bucketInfo[bucket].numMove; @@ -909,10 +904,11 @@ GetBlocks(cachePtr, bucket) } if (cachePtr->buckets[bucket].numFree == 0) { + register size_t size; /* - * If no blocks could be moved from shared, first look for a - * larger block in this cache to split up. + * If no blocks could be moved from shared, first look for a larger + * block in this cache to split up. */ blockPtr = NULL; @@ -962,8 +958,8 @@ GetBlocks(cachePtr, bucket) * * TclFinalizeThreadAlloc -- * - * This procedure is used to destroy all private resources used in - * this file. + * This procedure is used to destroy all private resources used in this + * file. * * Results: * None. @@ -979,7 +975,7 @@ TclFinalizeThreadAlloc() { int i; for (i = 0; i < NBUCKETS; ++i) { - TclpFreeAllocMutex(bucketInfo[i].lockPtr); + TclpFreeAllocMutex(bucketInfo[i].lockPtr); bucketInfo[i].lockPtr = NULL; } @@ -993,14 +989,13 @@ TclFinalizeThreadAlloc() } #else - /* *---------------------------------------------------------------------- * * TclFinalizeThreadAlloc -- * - * This procedure is used to destroy all private resources used in - * this file. + * This procedure is used to destroy all private resources used in this + * file. * * Results: * None. @@ -1016,5 +1011,12 @@ TclFinalizeThreadAlloc() { Tcl_Panic("TclFinalizeThreadAlloc called when threaded memory allocator not in use."); } - #endif /* TCL_THREADS */ + +/* + * Local Variables: + * mode: c + * c-basic-offset: 4 + * fill-column: 78 + * End: + */ |