Create a generic cache for objects of same size

The suffix pool could be thread-local and use the generic cache

1 files changed, 146 insertions, 0 deletions

diff --git a/cache.c b/cache.c
new file mode 100644
index 0000000..636cf45
--- /dev/null
+++ b/cache.c
@@ -0,0 +1,146 @@
+/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#ifndef NDEBUG
+#include <signal.h>
+#endif
+
+#include "cache.h"
+
+#ifndef NDEBUG
+const uint64_t redzone_pattern = 0xdeadbeefcafebabe;
+int cache_error = 0;
+#endif
+
+const int initial_pool_size = 64;
+
+cache_t* cache_create(const char *name, size_t bufsize, size_t align,
+                      cache_constructor_t* constructor,
+                      cache_destructor_t* destructor) {
+    cache_t* ret = calloc(1, sizeof(cache_t));
+    char* nm = strdup(name);
+    void** ptr = calloc(initial_pool_size, bufsize);
+    if (ret == NULL || nm == NULL || ptr == NULL ||
+        pthread_mutex_init(&ret->mutex, NULL) == -1) {
+        free(ret);
+        free(nm);
+        free(ptr);
+        return NULL;
+    }
+
+    ret->name = nm;
+    ret->ptr = ptr;
+    ret->freetotal = initial_pool_size;
+    ret->constructor = constructor;
+    ret->destructor = destructor;
+
+#ifndef NDEBUG
+    ret->bufsize = bufsize + 2 * sizeof(redzone_pattern);
+#else
+    ret->bufsize = bufsize;
+#endif
+
+    return ret;
+}
+
+static inline void* get_object(void *ptr) {
+#ifndef NDEBUG
+    uint64_t *pre = ptr;
+    return pre + 1;
+#endif
+    return ptr;
+}
+
+void cache_destroy(cache_t *cache) {
+    while (cache->freecurr > 0) {
+        void *ptr = cache->ptr[--cache->freecurr];
+        if (cache->destructor) {
+            cache->destructor(get_object(ptr), NULL);
+        }
+        free(ptr);
+    }
+    free(cache->name);
+    free(cache->ptr);
+    pthread_mutex_destroy(&cache->mutex);
+}
+
+void* cache_alloc(cache_t *cache) {
+    void *ret;
+    void *object;
+    pthread_mutex_lock(&cache->mutex);
+    if (cache->freecurr > 0) {
+        ret = cache->ptr[--cache->freecurr];
+        object = get_object(ret);
+    } else {
+        object = ret = malloc(cache->bufsize);
+        if (ret != NULL) {
+            object = get_object(ret);
+
+            if (cache->constructor != NULL &&
+                cache->constructor(object, NULL, 0) != 0) {
+                free(ret);
+                object = NULL;
+            }
+        }
+    }
+    pthread_mutex_unlock(&cache->mutex);
+
+#ifndef NDEBUG
+    if (object != NULL) {
+        /* add a simple form of buffer-check */
+        uint64_t *pre = ret;
+        *pre = redzone_pattern;
+        ret = pre+1;
+        memcpy(((char*)ret) + cache->bufsize - (2 * sizeof(redzone_pattern)),
+               &redzone_pattern, sizeof(redzone_pattern));
+    }
+#endif
+
+    return object;
+}
+
+void cache_free(cache_t *cache, void *ptr) {
+    pthread_mutex_lock(&cache->mutex);
+
+#ifndef NDEBUG
+    /* validate redzone... */
+    if (memcmp(((char*)ptr) + cache->bufsize - (2 * sizeof(redzone_pattern)),
+               &redzone_pattern, sizeof(redzone_pattern)) != 0) {
+        raise(SIGABRT);
+        cache_error = 1;
+        pthread_mutex_unlock(&cache->mutex);
+        return;
+    }
+    uint64_t *pre = ptr;
+    --pre;
+    if (*pre != redzone_pattern) {
+        raise(SIGABRT);
+        cache_error = -1;
+        pthread_mutex_unlock(&cache->mutex);
+        return;
+    }
+    ptr = pre;
+#endif
+    if (cache->freecurr < cache->freetotal) {
+        cache->ptr[cache->freecurr++] = ptr;
+    } else {
+        /* try to enlarge free connections array */
+        size_t newtotal = cache->freetotal * 2;
+        void **new_free = realloc(cache->ptr, sizeof(char *) * newtotal);
+        if (new_free) {
+            cache->freetotal = newtotal;
+            cache->ptr = new_free;
+            cache->ptr[cache->freecurr++] = ptr;
+        } else {
+            if (cache->destructor) {
+                cache->destructor(ptr, NULL);
+            }
+            free(ptr);
+
+        }
+    }
+    pthread_mutex_unlock(&cache->mutex);
+}
+