Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/winpr/libwinpr/utils/collections/ObjectPool.c

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+/**
+ * WinPR: Windows Portable Runtime
+ * Object Pool
+ *
+ * Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <winpr/config.h>
+
+#include <winpr/crt.h>
+#include <winpr/assert.h>
+
+#include <winpr/collections.h>
+
+struct s_wObjectPool
+{
+	size_t size;
+	size_t capacity;
+	void** array;
+	CRITICAL_SECTION lock;
+	wObject object;
+	BOOL synchronized;
+};
+
+/**
+ * C Object Pool similar to C# BufferManager Class:
+ * http://msdn.microsoft.com/en-us/library/ms405814.aspx
+ */
+
+/**
+ * Methods
+ */
+
+static void ObjectPool_Lock(wObjectPool* pool)
+{
+	WINPR_ASSERT(pool);
+	if (pool->synchronized)
+		EnterCriticalSection(&pool->lock);
+}
+
+static void ObjectPool_Unlock(wObjectPool* pool)
+{
+	WINPR_ASSERT(pool);
+	if (pool->synchronized)
+		LeaveCriticalSection(&pool->lock);
+}
+
+/**
+ * Gets an object from the pool.
+ */
+
+void* ObjectPool_Take(wObjectPool* pool)
+{
+	void* obj = nullptr;
+
+	ObjectPool_Lock(pool);
+
+	if (pool->size > 0)
+		obj = pool->array[--(pool->size)];
+
+	if (!obj)
+	{
+		if (pool->object.fnObjectNew)
+			obj = pool->object.fnObjectNew(nullptr);
+	}
+
+	if (pool->object.fnObjectInit)
+		pool->object.fnObjectInit(obj);
+
+	ObjectPool_Unlock(pool);
+
+	return obj;
+}
+
+static BOOL ObjectPool_EnsureCapacity(wObjectPool* pool, size_t add)
+{
+	WINPR_ASSERT(pool->size < SIZE_MAX - add);
+
+	const size_t blocksize = 128ull;
+	const size_t required = pool->size + add;
+	if (required >= pool->capacity)
+	{
+		const size_t new_cap = required + blocksize - required % blocksize;
+
+		void** new_arr = (void**)realloc((void*)pool->array, sizeof(void*) * new_cap);
+		if (!new_arr)
+			return FALSE;
+
+		pool->array = new_arr;
+		pool->capacity = new_cap;
+	}
+	return TRUE;
+}
+
+/**
+ * Returns an object to the pool.
+ */
+
+void ObjectPool_Return(wObjectPool* pool, void* obj)
+{
+	ObjectPool_Lock(pool);
+
+	if (!ObjectPool_EnsureCapacity(pool, 1))
+		goto out;
+
+	pool->array[(pool->size)++] = obj;
+
+	if (pool->object.fnObjectUninit)
+		pool->object.fnObjectUninit(obj);
+
+out:
+	ObjectPool_Unlock(pool);
+}
+
+wObject* ObjectPool_Object(wObjectPool* pool)
+{
+	WINPR_ASSERT(pool);
+	return &pool->object;
+}
+
+/**
+ * Releases the buffers currently cached in the pool.
+ */
+
+void ObjectPool_Clear(wObjectPool* pool)
+{
+	ObjectPool_Lock(pool);
+
+	while (pool->size > 0)
+	{
+		(pool->size)--;
+
+		if (pool->object.fnObjectFree)
+			pool->object.fnObjectFree(pool->array[pool->size]);
+	}
+
+	ObjectPool_Unlock(pool);
+}
+
+/**
+ * Construction, Destruction
+ */
+
+wObjectPool* ObjectPool_New(BOOL synchronized)
+{
+	wObjectPool* pool = (wObjectPool*)calloc(1, sizeof(wObjectPool));
+
+	if (!pool)
+		goto fail;
+
+	pool->synchronized = synchronized;
+
+	if (pool->synchronized)
+	{
+		if (!InitializeCriticalSectionAndSpinCount(&pool->lock, 4000))
+			goto fail;
+	}
+
+	if (!ObjectPool_EnsureCapacity(pool, 32))
+		goto fail;
+
+	return pool;
+
+fail:
+	ObjectPool_Free(pool);
+	return nullptr;
+}
+
+void ObjectPool_Free(wObjectPool* pool)
+{
+	if (!pool)
+		return;
+
+	ObjectPool_Clear(pool);
+
+	if (pool->synchronized)
+		DeleteCriticalSection(&pool->lock);
+
+	free((void*)pool->array);
+
+	free(pool);
+}