--- /dev/null
+/*
+ * 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
+ * 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.
+ *
+ * RCS: @(#) $Id$ */
+
+#if defined(TCL_THREADS) && defined(USE_THREAD_ALLOC)
+
+#include "tclInt.h"
+
+#ifdef WIN32
+#include "tclWinInt.h"
+#else
+extern Tcl_Mutex *TclpNewAllocMutex(void);
+extern void *TclpGetAllocCache(void);
+extern void TclpSetAllocCache(void *);
+#endif
+
+/*
+ * 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
+#ifdef NDEBUG
+#define RCHECK 0
+#else
+#define RCHECK 1
+#endif
+#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.
+ *
+ */
+
+#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))
+ */
+
+#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.
+ */
+
+typedef struct Block {
+ union {
+ struct Block *next; /* Next in free list. */
+ struct {
+ unsigned char magic1; /* First magic number. */
+ unsigned char bucket; /* Bucket block allocated from. */
+ unsigned char unused; /* Padding. */
+ unsigned char magic2; /* Second magic number. */
+ } b_s;
+ } b_u;
+ size_t b_reqsize; /* Requested allocation size. */
+} Block;
+#define b_next b_u.next
+#define b_bucket b_u.b_s.bucket
+#define b_magic1 b_u.b_s.magic1
+#define b_magic2 b_u.b_s.magic2
+#define MAGIC 0xef
+
+/*
+ * The following structure defines a bucket of blocks with
+ * various accounting and statistics information.
+ */
+
+typedef struct Bucket {
+ Block *firstPtr;
+ int nfree;
+ int nget;
+ int nput;
+ int nwait;
+ int nlock;
+ int nrequest;
+} Bucket;
+
+/*
+ * The following structure defines a cache of buckets and objs.
+ */
+
+typedef struct Cache {
+ struct Cache *nextPtr;
+ Tcl_ThreadId owner;
+ Tcl_Obj *firstObjPtr;
+ int nobjs;
+ int nsysalloc;
+ Bucket buckets[NBUCKETS];
+} Cache;
+
+/*
+ * The following array specifies various per-bucket
+ * limits and locks. The values are statically initialized
+ * to avoid calculating them repeatedly.
+ */
+
+struct binfo {
+ size_t blocksize; /* Bucket blocksize. */
+ int maxblocks; /* Max blocks before move to share. */
+ int nmove; /* Num blocks to move to share. */
+ Tcl_Mutex *lockPtr; /* Share bucket lock. */
+} binfo[NBUCKETS] = {
+ { 16, 1024, 512, NULL},
+ { 32, 512, 256, NULL},
+ { 64, 256, 128, NULL},
+ { 128, 128, 64, NULL},
+ { 256, 64, 32, NULL},
+ { 512, 32, 16, NULL},
+ { 1024, 16, 8, NULL},
+ { 2048, 8, 4, NULL},
+ { 4096, 4, 2, NULL},
+ { 8192, 2, 1, NULL},
+ {16284, 1, 1, NULL},
+};
+
+/*
+ * Static functions defined in this file.
+ */
+
+static void LockBucket(Cache *cachePtr, int bucket);
+static void UnlockBucket(Cache *cachePtr, int bucket);
+static void PutBlocks(Cache *cachePtr, int bucket, int nmove);
+static int GetBlocks(Cache *cachePtr, int bucket);
+static Block *Ptr2Block(char *ptr);
+static char *Block2Ptr(Block *blockPtr, int bucket, unsigned int reqsize);
+static void MoveObjs(Cache *fromPtr, Cache *toPtr, int nmove);
+
+/*
+ * Local variables defined in this file and initialized at
+ * startup.
+ */
+
+static Tcl_Mutex *listLockPtr;
+static Tcl_Mutex *objLockPtr;
+static Cache sharedCache;
+static Cache *sharedPtr = &sharedCache;
+static Cache *firstCachePtr = &sharedCache;
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetCache ---
+ *
+ * Gets per-thread memory cache, allocating it if necessary.
+ *
+ * Results:
+ * Pointer to cache.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static Cache *
+GetCache(void)
+{
+ Cache *cachePtr;
+
+ /*
+ * Check for first-time initialization.
+ */
+
+ if (listLockPtr == NULL) {
+ Tcl_Mutex *initLockPtr;
+ int i;
+
+ initLockPtr = Tcl_GetAllocMutex();
+ Tcl_MutexLock(initLockPtr);
+ if (listLockPtr == NULL) {
+ listLockPtr = TclpNewAllocMutex();
+ objLockPtr = TclpNewAllocMutex();
+ for (i = 0; i < NBUCKETS; ++i) {
+ binfo[i].lockPtr = TclpNewAllocMutex();
+ }
+ }
+ Tcl_MutexUnlock(initLockPtr);
+ }
+
+ /*
+ * Get this thread's cache, allocating if necessary.
+ */
+
+ cachePtr = TclpGetAllocCache();
+ if (cachePtr == NULL) {
+ cachePtr = calloc(1, sizeof(Cache));
+ if (cachePtr == NULL) {
+ panic("alloc: could not allocate new cache");
+ }
+ Tcl_MutexLock(listLockPtr);
+ cachePtr->nextPtr = firstCachePtr;
+ firstCachePtr = cachePtr;
+ Tcl_MutexUnlock(listLockPtr);
+ cachePtr->owner = Tcl_GetCurrentThread();
+ TclpSetAllocCache(cachePtr);
+ }
+ return cachePtr;
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclFreeAllocCache --
+ *
+ * Flush and delete a cache, removing from list of caches.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclFreeAllocCache(void *arg)
+{
+ Cache *cachePtr = arg;
+ Cache **nextPtrPtr;
+ register int bucket;
+
+ /*
+ * Flush blocks.
+ */
+
+ for (bucket = 0; bucket < NBUCKETS; ++bucket) {
+ if (cachePtr->buckets[bucket].nfree > 0) {
+ PutBlocks(cachePtr, bucket, cachePtr->buckets[bucket].nfree);
+ }
+ }
+
+ /*
+ * Flush objs.
+ */
+
+ if (cachePtr->nobjs > 0) {
+ Tcl_MutexLock(objLockPtr);
+ MoveObjs(cachePtr, sharedPtr, cachePtr->nobjs);
+ Tcl_MutexUnlock(objLockPtr);
+ }
+
+ /*
+ * Remove from pool list.
+ */
+
+ Tcl_MutexLock(listLockPtr);
+ nextPtrPtr = &firstCachePtr;
+ while (*nextPtrPtr != cachePtr) {
+ nextPtrPtr = &(*nextPtrPtr)->nextPtr;
+ }
+ *nextPtrPtr = cachePtr->nextPtr;
+ cachePtr->nextPtr = NULL;
+ Tcl_MutexUnlock(listLockPtr);
+#ifdef WIN32
+ TlsFree((DWORD) cachePtr);
+#else
+ free(cachePtr);
+#endif
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpAlloc --
+ *
+ * Allocate memory.
+ *
+ * Results:
+ * Pointer to memory just beyond Block pointer.
+ *
+ * Side effects:
+ * May allocate more blocks for a bucket.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+TclpAlloc(unsigned int reqsize)
+{
+ Cache *cachePtr = TclpGetAllocCache();
+ Block *blockPtr;
+ register int bucket;
+ size_t size;
+
+ if (cachePtr == NULL) {
+ cachePtr = GetCache();
+ }
+
+ /*
+ * 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.
+ */
+
+ blockPtr = NULL;
+ size = reqsize + sizeof(Block);
+#if RCHECK
+ ++size;
+#endif
+ if (size > MAXALLOC) {
+ bucket = NBUCKETS;
+ blockPtr = malloc(size);
+ if (blockPtr != NULL) {
+ cachePtr->nsysalloc += reqsize;
+ }
+ } else {
+ bucket = 0;
+ while (binfo[bucket].blocksize < size) {
+ ++bucket;
+ }
+ if (cachePtr->buckets[bucket].nfree || GetBlocks(cachePtr, bucket)) {
+ blockPtr = cachePtr->buckets[bucket].firstPtr;
+ cachePtr->buckets[bucket].firstPtr = blockPtr->b_next;
+ --cachePtr->buckets[bucket].nfree;
+ ++cachePtr->buckets[bucket].nget;
+ cachePtr->buckets[bucket].nrequest += reqsize;
+ }
+ }
+ if (blockPtr == NULL) {
+ return NULL;
+ }
+ return Block2Ptr(blockPtr, bucket, reqsize);
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpFree --
+ *
+ * Return blocks to the thread block cache.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * May move blocks to shared cache.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclpFree(char *ptr)
+{
+ if (ptr != NULL) {
+ Cache *cachePtr = TclpGetAllocCache();
+ Block *blockPtr;
+ int bucket;
+
+ if (cachePtr == NULL) {
+ cachePtr = GetCache();
+ }
+
+ /*
+ * 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);
+ bucket = blockPtr->b_bucket;
+ if (bucket == NBUCKETS) {
+ cachePtr->nsysalloc -= blockPtr->b_reqsize;
+ free(blockPtr);
+ } else {
+ cachePtr->buckets[bucket].nrequest -= blockPtr->b_reqsize;
+ blockPtr->b_next = cachePtr->buckets[bucket].firstPtr;
+ cachePtr->buckets[bucket].firstPtr = blockPtr;
+ ++cachePtr->buckets[bucket].nfree;
+ ++cachePtr->buckets[bucket].nput;
+ if (cachePtr != sharedPtr &&
+ cachePtr->buckets[bucket].nfree > binfo[bucket].maxblocks) {
+ PutBlocks(cachePtr, bucket, binfo[bucket].nmove);
+ }
+ }
+ }
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpRealloc --
+ *
+ * Re-allocate memory to a larger or smaller size.
+ *
+ * Results:
+ * Pointer to memory just beyond Block pointer.
+ *
+ * Side effects:
+ * Previous memory, if any, may be freed.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+TclpRealloc(char *ptr, unsigned int reqsize)
+{
+ Cache *cachePtr = TclpGetAllocCache();
+ Block *blockPtr;
+ void *new;
+ size_t size, min;
+ int bucket;
+
+ if (ptr == NULL) {
+ return TclpAlloc(reqsize);
+ }
+
+ if (cachePtr == NULL) {
+ cachePtr = GetCache();
+ }
+
+ /*
+ * 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);
+ size = reqsize + sizeof(Block);
+#if RCHECK
+ ++size;
+#endif
+ bucket = blockPtr->b_bucket;
+ if (bucket != NBUCKETS) {
+ if (bucket > 0) {
+ min = binfo[bucket-1].blocksize;
+ } else {
+ min = 0;
+ }
+ if (size > min && size <= binfo[bucket].blocksize) {
+ cachePtr->buckets[bucket].nrequest -= blockPtr->b_reqsize;
+ cachePtr->buckets[bucket].nrequest += reqsize;
+ return Block2Ptr(blockPtr, bucket, reqsize);
+ }
+ } else if (size > MAXALLOC) {
+ cachePtr->nsysalloc -= blockPtr->b_reqsize;
+ cachePtr->nsysalloc += reqsize;
+ blockPtr = realloc(blockPtr, size);
+ if (blockPtr == NULL) {
+ return NULL;
+ }
+ return Block2Ptr(blockPtr, NBUCKETS, reqsize);
+ }
+
+ /*
+ * Finally, perform an expensive malloc/copy/free.
+ */
+
+ new = TclpAlloc(reqsize);
+ if (new != NULL) {
+ if (reqsize > blockPtr->b_reqsize) {
+ reqsize = blockPtr->b_reqsize;
+ }
+ memcpy(new, ptr, reqsize);
+ TclpFree(ptr);
+ }
+ return new;
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclThreadAllocObj --
+ *
+ * Allocate a Tcl_Obj from the per-thread cache.
+ *
+ * Results:
+ * 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.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Obj *
+TclThreadAllocObj(void)
+{
+ register Cache *cachePtr = TclpGetAllocCache();
+ register int nmove;
+ 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.
+ */
+
+ if (cachePtr->nobjs == 0) {
+ Tcl_MutexLock(objLockPtr);
+ nmove = sharedPtr->nobjs;
+ if (nmove > 0) {
+ if (nmove > NOBJALLOC) {
+ nmove = NOBJALLOC;
+ }
+ MoveObjs(sharedPtr, cachePtr, nmove);
+ }
+ Tcl_MutexUnlock(objLockPtr);
+ if (cachePtr->nobjs == 0) {
+ cachePtr->nobjs = nmove = NOBJALLOC;
+ newObjsPtr = malloc(sizeof(Tcl_Obj) * nmove);
+ if (newObjsPtr == NULL) {
+ panic("alloc: could not allocate %d new objects", nmove);
+ }
+ while (--nmove >= 0) {
+ objPtr = &newObjsPtr[nmove];
+ objPtr->internalRep.otherValuePtr = cachePtr->firstObjPtr;
+ cachePtr->firstObjPtr = objPtr;
+ }
+ }
+ }
+
+ /*
+ * Pop the first object.
+ */
+
+ objPtr = cachePtr->firstObjPtr;
+ cachePtr->firstObjPtr = objPtr->internalRep.otherValuePtr;
+ --cachePtr->nobjs;
+ return objPtr;
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclThreadFreeObj --
+ *
+ * Return a free Tcl_Obj to the per-thread cache.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * May move free Tcl_Obj's to shared list upon hitting high
+ * water mark.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclThreadFreeObj(Tcl_Obj *objPtr)
+{
+ Cache *cachePtr = TclpGetAllocCache();
+
+ if (cachePtr == NULL) {
+ cachePtr = GetCache();
+ }
+
+ /*
+ * Get this thread's list and push on the free Tcl_Obj.
+ */
+
+ objPtr->internalRep.otherValuePtr = cachePtr->firstObjPtr;
+ cachePtr->firstObjPtr = objPtr;
+ ++cachePtr->nobjs;
+
+ /*
+ * If the number of free objects has exceeded the high
+ * water mark, move some blocks to the shared list.
+ */
+
+ if (cachePtr->nobjs > NOBJHIGH) {
+ Tcl_MutexLock(objLockPtr);
+ MoveObjs(cachePtr, sharedPtr, NOBJALLOC);
+ Tcl_MutexUnlock(objLockPtr);
+ }
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_GetMemoryInfo --
+ *
+ * Return a list-of-lists of memory stats.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * List appended to given dstring.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_GetMemoryInfo(Tcl_DString *dsPtr)
+{
+ Cache *cachePtr;
+ char buf[200];
+ int n;
+
+ Tcl_MutexLock(listLockPtr);
+ cachePtr = firstCachePtr;
+ while (cachePtr != NULL) {
+ Tcl_DStringStartSublist(dsPtr);
+ if (cachePtr == sharedPtr) {
+ Tcl_DStringAppendElement(dsPtr, "shared");
+ } else {
+ sprintf(buf, "thread%d", (int) cachePtr->owner);
+ Tcl_DStringAppendElement(dsPtr, buf);
+ }
+ for (n = 0; n < NBUCKETS; ++n) {
+ sprintf(buf, "%d %d %d %d %d %d %d",
+ (int) binfo[n].blocksize,
+ cachePtr->buckets[n].nfree,
+ cachePtr->buckets[n].nget,
+ cachePtr->buckets[n].nput,
+ cachePtr->buckets[n].nrequest,
+ cachePtr->buckets[n].nlock,
+ cachePtr->buckets[n].nwait);
+ Tcl_DStringAppendElement(dsPtr, buf);
+ }
+ Tcl_DStringEndSublist(dsPtr);
+ cachePtr = cachePtr->nextPtr;
+ }
+ Tcl_MutexUnlock(listLockPtr);
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * MoveObjs --
+ *
+ * Move Tcl_Obj's between caches.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+MoveObjs(Cache *fromPtr, Cache *toPtr, int nmove)
+{
+ register Tcl_Obj *objPtr = fromPtr->firstObjPtr;
+ Tcl_Obj *fromFirstObjPtr = objPtr;
+
+ toPtr->nobjs += nmove;
+ fromPtr->nobjs -= nmove;
+
+ /*
+ * 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 (--nmove) {
+ objPtr = objPtr->internalRep.otherValuePtr;
+ }
+ 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.
+ */
+
+ objPtr->internalRep.otherValuePtr = toPtr->firstObjPtr;
+ toPtr->firstObjPtr = fromFirstObjPtr;
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * Block2Ptr, Ptr2Block --
+ *
+ * Convert between internal blocks and user pointers.
+ *
+ * Results:
+ * User pointer or internal block.
+ *
+ * Side effects:
+ * Invalid blocks will abort the server.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static char *
+Block2Ptr(Block *blockPtr, int bucket, unsigned int reqsize)
+{
+ register void *ptr;
+
+ blockPtr->b_magic1 = blockPtr->b_magic2 = MAGIC;
+ blockPtr->b_bucket = bucket;
+ blockPtr->b_reqsize = reqsize;
+ ptr = ((void *) (blockPtr + 1));
+#if RCHECK
+ ((unsigned char *)(ptr))[reqsize] = MAGIC;
+#endif
+ return (char *) ptr;
+}
+
+static Block *
+Ptr2Block(char *ptr)
+{
+ register Block *blockPtr;
+
+ blockPtr = (((Block *) ptr) - 1);
+ if (blockPtr->b_magic1 != MAGIC
+#if RCHECK
+ || ((unsigned char *) ptr)[blockPtr->b_reqsize] != MAGIC
+#endif
+ || blockPtr->b_magic2 != MAGIC) {
+ panic("alloc: invalid block: %p: %x %x %x\n",
+ blockPtr, blockPtr->b_magic1, blockPtr->b_magic2,
+ ((unsigned char *) ptr)[blockPtr->b_reqsize]);
+ }
+ return blockPtr;
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * LockBucket, UnlockBucket --
+ *
+ * Set/unset the lock to access a bucket in the shared cache.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * Lock activity and contention are monitored globally and on
+ * a per-cache basis.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+LockBucket(Cache *cachePtr, int bucket)
+{
+#if 0
+ if (Tcl_MutexTryLock(binfo[bucket].lockPtr) != TCL_OK) {
+ Tcl_MutexLock(binfo[bucket].lockPtr);
+ ++cachePtr->buckets[bucket].nwait;
+ ++sharedPtr->buckets[bucket].nwait;
+ }
+#else
+ Tcl_MutexLock(binfo[bucket].lockPtr);
+#endif
+ ++cachePtr->buckets[bucket].nlock;
+ ++sharedPtr->buckets[bucket].nlock;
+}
+
+
+static void
+UnlockBucket(Cache *cachePtr, int bucket)
+{
+ Tcl_MutexUnlock(binfo[bucket].lockPtr);
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * PutBlocks --
+ *
+ * Return unused blocks to the shared cache.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+PutBlocks(Cache *cachePtr, int bucket, int nmove)
+{
+ register Block *lastPtr, *firstPtr;
+ register int n = nmove;
+
+ /*
+ * Before acquiring the lock, walk the block list to find
+ * the last block to be moved.
+ */
+
+ firstPtr = lastPtr = cachePtr->buckets[bucket].firstPtr;
+ while (--n > 0) {
+ lastPtr = lastPtr->b_next;
+ }
+ cachePtr->buckets[bucket].firstPtr = lastPtr->b_next;
+ cachePtr->buckets[bucket].nfree -= nmove;
+
+ /*
+ * Aquire the lock and place the list of blocks at the front
+ * of the shared cache bucket.
+ */
+
+ LockBucket(cachePtr, bucket);
+ lastPtr->b_next = sharedPtr->buckets[bucket].firstPtr;
+ sharedPtr->buckets[bucket].firstPtr = firstPtr;
+ sharedPtr->buckets[bucket].nfree += nmove;
+ UnlockBucket(cachePtr, bucket);
+}
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetBlocks --
+ *
+ * Get more blocks for a bucket.
+ *
+ * Results:
+ * 1 if blocks where allocated, 0 otherwise.
+ *
+ * Side effects:
+ * Cache may be filled with available blocks.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+GetBlocks(Cache *cachePtr, int 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 nfree 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].nfree > 0) {
+ LockBucket(cachePtr, bucket);
+ if (sharedPtr->buckets[bucket].nfree > 0) {
+
+ /*
+ * Either move the entire list or walk the list to find
+ * the last block to move.
+ */
+
+ n = binfo[bucket].nmove;
+ if (n >= sharedPtr->buckets[bucket].nfree) {
+ cachePtr->buckets[bucket].firstPtr =
+ sharedPtr->buckets[bucket].firstPtr;
+ cachePtr->buckets[bucket].nfree =
+ sharedPtr->buckets[bucket].nfree;
+ sharedPtr->buckets[bucket].firstPtr = NULL;
+ sharedPtr->buckets[bucket].nfree = 0;
+ } else {
+ blockPtr = sharedPtr->buckets[bucket].firstPtr;
+ cachePtr->buckets[bucket].firstPtr = blockPtr;
+ sharedPtr->buckets[bucket].nfree -= n;
+ cachePtr->buckets[bucket].nfree = n;
+ while (--n > 0) {
+ blockPtr = blockPtr->b_next;
+ }
+ sharedPtr->buckets[bucket].firstPtr = blockPtr->b_next;
+ blockPtr->b_next = NULL;
+ }
+ }
+ UnlockBucket(cachePtr, bucket);
+ }
+
+ if (cachePtr->buckets[bucket].nfree == 0) {
+
+ /*
+ * If no blocks could be moved from shared, first look for a
+ * larger block in this cache to split up.
+ */
+
+ blockPtr = NULL;
+ n = NBUCKETS;
+ size = 0; /* lint */
+ while (--n > bucket) {
+ if (cachePtr->buckets[n].nfree > 0) {
+ size = binfo[n].blocksize;
+ blockPtr = cachePtr->buckets[n].firstPtr;
+ cachePtr->buckets[n].firstPtr = blockPtr->b_next;
+ --cachePtr->buckets[n].nfree;
+ break;
+ }
+ }
+
+ /*
+ * Otherwise, allocate a big new block directly.
+ */
+
+ if (blockPtr == NULL) {
+ size = MAXALLOC;
+ blockPtr = malloc(size);
+ if (blockPtr == NULL) {
+ return 0;
+ }
+ }
+
+ /*
+ * Split the larger block into smaller blocks for this bucket.
+ */
+
+ n = size / binfo[bucket].blocksize;
+ cachePtr->buckets[bucket].nfree = n;
+ cachePtr->buckets[bucket].firstPtr = blockPtr;
+ while (--n > 0) {
+ blockPtr->b_next = (Block *)
+ ((char *) blockPtr + binfo[bucket].blocksize);
+ blockPtr = blockPtr->b_next;
+ }
+ blockPtr->b_next = NULL;
+ }
+ return 1;
+}
+
+#endif /* TCL_THREADS */
--- /dev/null
+/*
+ * tclThreadJoin.c --
+ *
+ * This file implements a platform independent emulation layer for
+ * the handling of joinable threads. The Mac and Windows platforms
+ * use this code to provide the functionality of joining threads.
+ * This code is currently not necessary on Unix.
+ *
+ * Copyright (c) 2000 by Scriptics Corporation
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * RCS: @(#) $Id$
+ */
+
+#include "tclInt.h"
+
+#if defined(WIN32) || defined(MAC_TCL)
+
+/* The information about each joinable thread is remembered in a
+ * structure as defined below.
+ */
+
+typedef struct JoinableThread {
+ Tcl_ThreadId id; /* The id of the joinable thread */
+ int result; /* A place for the result after the
+ * demise of the thread */
+ int done; /* Boolean flag. Initialized to 0
+ * and set to 1 after the exit of
+ * the thread. This allows a thread
+ * requesting a join to detect when
+ * waiting is not necessary. */
+ int waitedUpon; /* Boolean flag. Initialized to 0
+ * and set to 1 by the thread waiting
+ * for this one via Tcl_JoinThread.
+ * Used to lock any other thread
+ * trying to wait on this one.
+ */
+ Tcl_Mutex threadMutex; /* The mutex used to serialize access
+ * to this structure. */
+ Tcl_Condition cond; /* This is the condition a thread has
+ * to wait upon to get notified of the
+ * end of the described thread. It is
+ * signaled indirectly by
+ * Tcl_ExitThread. */
+ struct JoinableThread* nextThreadPtr; /* Reference to the next thread in the
+ * list of joinable threads */
+} JoinableThread;
+
+/* The following variable is used to maintain the global list of all
+ * joinable threads. Usage by a thread is allowed only if the
+ * thread acquired the 'joinMutex'.
+ */
+
+TCL_DECLARE_MUTEX(joinMutex)
+
+static JoinableThread* firstThreadPtr;
+
+
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclJoinThread --
+ *
+ * This procedure waits for the exit of the thread with the specified
+ * id and returns its result.
+ *
+ * Results:
+ * A standard tcl result signaling the overall success/failure of the
+ * operation and an integer result delivered by the thread which was
+ * waited upon.
+ *
+ * Side effects:
+ * Deallocates the memory allocated by TclRememberJoinableThread.
+ * Removes the data associated to the thread waited upon from the
+ * list of joinable threads.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclJoinThread(id, result)
+ Tcl_ThreadId id; /* The id of the thread to wait upon. */
+ int* result; /* Reference to a location for the result
+ * of the thread we are waiting upon. */
+{
+ /* Steps done here:
+ * i. Acquire the joinMutex and search for the thread.
+ * ii. Error out if it could not be found.
+ * iii. If found, switch from exclusive access to the list to exclusive
+ * access to the thread structure.
+ * iv. Error out if some other is already waiting.
+ * v. Skip the waiting part of the thread is already done.
+ * vi. Wait for the thread to exit, mark it as waited upon too.
+ * vii. Get the result form the structure,
+ * viii. switch to exclusive access of the list,
+ * ix. remove the structure from the list,
+ * x. then switch back to exclusive access to the structure
+ * xi. and delete it.
+ */
+
+ JoinableThread* threadPtr;
+
+ Tcl_MutexLock (&joinMutex);
+
+ for (threadPtr = firstThreadPtr;
+ (threadPtr != (JoinableThread*) NULL) && (threadPtr->id != id);
+ threadPtr = threadPtr->nextThreadPtr)
+ /* empty body */
+ ;
+
+ if (threadPtr == (JoinableThread*) NULL) {
+ /* Thread not found. Either not joinable, or already waited
+ * upon and exited. Whatever, an error is in order.
+ */
+
+ Tcl_MutexUnlock (&joinMutex);
+ return TCL_ERROR;
+ }
+
+ /* [1] If we don't lock the structure before giving up exclusive access
+ * to the list some other thread just completing its wait on the same
+ * thread can delete the structure from under us, leaving us with a
+ * dangling pointer.
+ */
+
+ Tcl_MutexLock (&threadPtr->threadMutex);
+ Tcl_MutexUnlock (&joinMutex);
+
+ /* [2] Now that we have the structure mutex any other thread that just
+ * tries to delete structure will wait at location [3] until we are
+ * done with the structure. And in that case we are done with it
+ * rather quickly as 'waitedUpon' will be set and we will have to
+ * error out.
+ */
+
+ if (threadPtr->waitedUpon) {
+ Tcl_MutexUnlock (&threadPtr->threadMutex);
+ return TCL_ERROR;
+ }
+
+ /* We are waiting now, let other threads recognize this
+ */
+
+ threadPtr->waitedUpon = 1;
+
+ while (!threadPtr->done) {
+ Tcl_ConditionWait (&threadPtr->cond, &threadPtr->threadMutex, NULL);
+ }
+
+ /* We have to release the structure before trying to access the list
+ * again or we can run into deadlock with a thread at [1] (see above)
+ * because of us holding the structure and the other holding the list.
+ * There is no problem with dangling pointers here as 'waitedUpon == 1'
+ * is still valid and any other thread will error out and not come to
+ * this place. IOW, the fact that we are here also means that no other
+ * thread came here before us and is able to delete the structure.
+ */
+
+ Tcl_MutexUnlock (&threadPtr->threadMutex);
+ Tcl_MutexLock (&joinMutex);
+
+ /* We have to search the list again as its structure may (may, almost
+ * certainly) have changed while we were waiting. Especially now is the
+ * time to compute the predecessor in the list. Any earlier result can
+ * be dangling by now.
+ */
+
+ if (firstThreadPtr == threadPtr) {
+ firstThreadPtr = threadPtr->nextThreadPtr;
+ } else {
+ JoinableThread* prevThreadPtr;
+
+ for (prevThreadPtr = firstThreadPtr;
+ prevThreadPtr->nextThreadPtr != threadPtr;
+ prevThreadPtr = prevThreadPtr->nextThreadPtr)
+ /* empty body */
+ ;
+
+ prevThreadPtr->nextThreadPtr = threadPtr->nextThreadPtr;
+ }
+
+ Tcl_MutexUnlock (&joinMutex);
+
+ /* [3] Now that the structure is not part of the list anymore no other
+ * thread can acquire its mutex from now on. But it is possible that
+ * another thread is still holding the mutex though, see location [2].
+ * So we have to acquire the mutex one more time to wait for that thread
+ * to finish. We can (and have to) release the mutex immediately.
+ */
+
+ Tcl_MutexLock (&threadPtr->threadMutex);
+ Tcl_MutexUnlock (&threadPtr->threadMutex);
+
+ /* Copy the result to us, finalize the synchronisation objects, then
+ * free the structure and return.
+ */
+
+ *result = threadPtr->result;
+
+ Tcl_ConditionFinalize (&threadPtr->cond);
+ Tcl_MutexFinalize (&threadPtr->threadMutex);
+ ckfree ((VOID*) threadPtr);
+
+ return TCL_OK;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclRememberJoinableThread --
+ *
+ * This procedure remebers a thread as joinable. Only a call to
+ * TclJoinThread will remove the structre created (and initialized)
+ * here. IOW, not waiting upon a joinable thread will cause memory
+ * leaks.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * Allocates memory, adds it to the global list of all joinable
+ * threads.
+ *
+ *----------------------------------------------------------------------
+ */
+
+VOID
+TclRememberJoinableThread(id)
+ Tcl_ThreadId id; /* The thread to remember as joinable */
+{
+ JoinableThread* threadPtr;
+
+ threadPtr = (JoinableThread*) ckalloc (sizeof (JoinableThread));
+ threadPtr->id = id;
+ threadPtr->done = 0;
+ threadPtr->waitedUpon = 0;
+ threadPtr->threadMutex = (Tcl_Mutex) NULL;
+ threadPtr->cond = (Tcl_Condition) NULL;
+
+ Tcl_MutexLock (&joinMutex);
+
+ threadPtr->nextThreadPtr = firstThreadPtr;
+ firstThreadPtr = threadPtr;
+
+ Tcl_MutexUnlock (&joinMutex);
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclSignalExitThread --
+ *
+ * This procedure signals that the specified thread is done with
+ * its work. If the thread is joinable this signal is propagated
+ * to the thread waiting upon it.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * Modifies the associated structure to hold the result.
+ *
+ *----------------------------------------------------------------------
+ */
+
+VOID
+TclSignalExitThread(id,result)
+ Tcl_ThreadId id; /* Id of the thread signaling its exit */
+ int result; /* The result from the thread */
+{
+ JoinableThread* threadPtr;
+
+ Tcl_MutexLock (&joinMutex);
+
+ for (threadPtr = firstThreadPtr;
+ (threadPtr != (JoinableThread*) NULL) && (threadPtr->id != id);
+ threadPtr = threadPtr->nextThreadPtr)
+ /* empty body */
+ ;
+
+ if (threadPtr == (JoinableThread*) NULL) {
+ /* Thread not found. Not joinable. No problem, nothing to do.
+ */
+
+ Tcl_MutexUnlock (&joinMutex);
+ return;
+ }
+
+ /* Switch over the exclusive access from the list to the structure,
+ * then store the result, set the flag and notify the waiting thread,
+ * provided that it exists. The order of lock/unlock ensures that a
+ * thread entering 'TclJoinThread' will not interfere with us.
+ */
+
+ Tcl_MutexLock (&threadPtr->threadMutex);
+ Tcl_MutexUnlock (&joinMutex);
+
+ threadPtr->done = 1;
+ threadPtr->result = result;
+
+ if (threadPtr->waitedUpon) {
+ Tcl_ConditionNotify (&threadPtr->cond);
+ }
+
+ Tcl_MutexUnlock (&threadPtr->threadMutex);
+}
+
+#endif /* WIN32 || MAC_TCL */
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