Add object pool

engine/CMakeLists.txt

@@ -37,6 +37,7 @@ set(BreezeSources
 
         breeze/utils/array.c
         breeze/utils/heap.c
+        breeze/utils/object_pool.c
         breeze/utils/tokenizer.c
     )
 
@@ -51,6 +52,7 @@ set(BreezeHeaders
 
         breeze/utils/array.h
         breeze/utils/heap.h
+        breeze/utils/object_pool.h
         breeze/utils/string.h
         breeze/utils/tokenizer.h
 

engine/breeze/utils/object_pool.c

@@ -0,0 +1,61 @@
+#include "object_pool.h"
+
+#include "../core/memory.h"
+
+typedef struct BzObjectPool {
+    void *objects;
+    size_t stride;
+    size_t numObjects;
+    i32 firstFree;
+} BzObjectPool;
+
+static i32 *bzObjectPoolGetObject(const BzObjectPool *pool, size_t idx) {
+    return (i32 *) ((u8 *) pool->objects + idx * pool->stride);
+}
+
+BzObjectPool *bzObjectPoolCreate(const BzObjectPoolDesc *desc) {
+    BZ_ASSERT(desc->objectSize > 0);
+
+    // NOTE: Since object bits are used as a free list
+    // when not in use, we must ensure they can hold i32.
+    size_t stride = desc->objectSize;
+    if (stride < sizeof(i32)) {
+        stride = sizeof(i32);
+    }
+
+    size_t numBytes = sizeof(BzObjectPool) + desc->numObjects * stride;
+    BzObjectPool *pool = bzAlloc(numBytes);
+    *pool = (BzObjectPool) {
+        .objects=pool + 1,
+        .stride=stride,
+        .numObjects=desc->numObjects,
+        .firstFree=0,
+    };
+
+    // Link free list
+    for (size_t i = 0; i < pool->numObjects - 1; i++) {
+        i32 *object = bzObjectPoolGetObject(pool, i);
+        *object = (i32) (i + 1);
+    }
+    i32 *lastObject = bzObjectPoolGetObject(pool, pool->numObjects - 1);
+    *lastObject = -1;
+
+    return pool;
+}
+void bzObjectPoolDestroy(BzObjectPool *pool) {
+    bzFree(pool);
+}
+
+void *bzObjectPool(BzObjectPool *pool) {
+    if (pool->firstFree == -1)
+        return NULL;
+    i32 *object = bzObjectPoolGetObject(pool, pool->firstFree);
+    pool->firstFree = *object;
+    return object;
+}
+void bzObjectPoolRelease(BzObjectPool *pool, void *object) {
+    size_t objectIdx = (size_t) object - (size_t)pool->objects;
+    BZ_ASSERT(objectIdx < pool->numObjects);
+    *(i32 *) objectIdx = pool->firstFree;
+    pool->firstFree = (i32) objectIdx;
+}

engine/breeze/utils/object_pool.h

@@ -0,0 +1,19 @@
+#ifndef BREEZE_OBJECT_POOL_H
+#define BREEZE_OBJECT_POOL_H
+
+#include "../defines.h"
+
+typedef struct BzObjectPool BzObjectPool;
+
+typedef struct BzObjectPoolDesc {
+    size_t objectSize;
+    size_t numObjects;
+} BzObjectPoolDesc;
+
+BzObjectPool *bzObjectPoolCreate(const BzObjectPoolDesc *desc);
+void bzObjectPoolDestroy(BzObjectPool *pool);
+
+void *bzObjectPool(BzObjectPool *pool);
+void bzObjectPoolRelease(BzObjectPool *pool, void *object);
+
+#endif //BREEZE_OBJECT_POOL_H