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/*
* (c)2014 Tweag I/O
*
* The Static Pointer Table implementation.
*
* https://gitlab.haskell.org/ghc/ghc/wikis/static-pointers
* https://gitlab.haskell.org/ghc/ghc/wikis/static-pointers/implementation-plan
*
*/
#include "Rts.h"
#include "StaticPtrTable.h"
#include "RtsUtils.h"
#include "Hash.h"
#include "StablePtr.h"
static HashTable * spt = NULL;
#if defined(THREADED_RTS)
static Mutex spt_lock;
#endif
/// Hash function for the SPT.
STATIC_INLINE int hashFingerprint(const HashTable *table, StgWord key) {
const StgWord64* ptr = (StgWord64*) key;
// Take half of the key to compute the hash.
return hashWord(table, *(ptr + 1));
}
/// Comparison function for the SPT.
STATIC_INLINE int compareFingerprint(StgWord a, StgWord b) {
const StgWord64* ptra = (StgWord64*) a;
const StgWord64* ptrb = (StgWord64*) b;
return *ptra == *ptrb && *(ptra + 1) == *(ptrb + 1);
}
void hs_spt_insert_stableptr(StgWord64 key[2], StgStablePtr *entry) {
// hs_spt_insert is called from constructor functions, so
// the SPT needs to be initialized here.
if (spt == NULL) {
spt = allocHashTable();
#if defined(THREADED_RTS)
initMutex(&spt_lock);
#endif
}
ACQUIRE_LOCK(&spt_lock);
insertHashTable_(spt, (StgWord)key, entry, hashFingerprint);
RELEASE_LOCK(&spt_lock);
}
void hs_spt_insert(StgWord64 key[2], void *spe_closure) {
// Cannot remove this indirection yet because getStablePtr()
// might return NULL, in which case hs_spt_lookup() returns NULL
// instead of the actual closure pointer.
StgStablePtr * entry = stgMallocBytes( sizeof(StgStablePtr)
, "hs_spt_insert: entry"
);
*entry = getStablePtr(spe_closure);
hs_spt_insert_stableptr(key, entry);
}
static void freeSptEntry(void* entry) {
freeStablePtr(*(StgStablePtr*)entry);
stgFree(entry);
}
void hs_spt_remove(StgWord64 key[2]) {
if (spt) {
ACQUIRE_LOCK(&spt_lock);
StgStablePtr* entry = removeHashTable_(spt, (StgWord)key, NULL,
hashFingerprint, compareFingerprint);
RELEASE_LOCK(&spt_lock);
if (entry)
freeSptEntry(entry);
}
}
StgPtr hs_spt_lookup(StgWord64 key[2]) {
if (spt) {
ACQUIRE_LOCK(&spt_lock);
const StgStablePtr * entry = lookupHashTable_(spt, (StgWord)key,
hashFingerprint, compareFingerprint);
const StgPtr ret = entry ? deRefStablePtr(*entry) : NULL;
RELEASE_LOCK(&spt_lock);
return ret;
} else
return NULL;
}
int hs_spt_keys(StgPtr keys[], int szKeys) {
if (spt) {
ACQUIRE_LOCK(&spt_lock);
const int ret = keysHashTable(spt, (StgWord*)keys, szKeys);
RELEASE_LOCK(&spt_lock);
return ret;
} else
return 0;
}
int hs_spt_key_count(void) {
return spt ? keyCountHashTable(spt) : 0;
}
void exitStaticPtrTable(void) {
if (spt) {
freeHashTable(spt, freeSptEntry);
spt = NULL;
#if defined(THREADED_RTS)
closeMutex(&spt_lock);
#endif
}
}
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