From 551fcf4fe39e68fab17d56cc6c4b8a61164891ff Mon Sep 17 00:00:00 2001
From: Chris Craik <ccraik@google.com>
Date: Wed, 5 Dec 2012 10:36:45 -0800
Subject: Add LinearAllocator

Moving from external/webkit/Source/WebCore/platform/graphics/android/utils/

Change-Id: If91830aa9b207dbc8692b2ca7c4a0b76778addd5
---
 include/utils/LinearAllocator.h | 97 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 include/utils/LinearAllocator.h

(limited to 'include/utils/LinearAllocator.h')

diff --git a/include/utils/LinearAllocator.h b/include/utils/LinearAllocator.h
new file mode 100644
index 0000000..4772bc8
--- /dev/null
+++ b/include/utils/LinearAllocator.h
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2012, The Android Open Source Project
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ANDROID_LINEARALLOCATOR_H
+#define ANDROID_LINEARALLOCATOR_H
+
+#include <stddef.h>
+
+namespace android {
+
+/**
+ * A memory manager that internally allocates multi-kbyte buffers for placing objects in. It avoids
+ * the overhead of malloc when many objects are allocated. It is most useful when creating many
+ * small objects with a similar lifetime, and doesn't add significant overhead for large
+ * allocations.
+ */
+class LinearAllocator {
+public:
+    LinearAllocator();
+    ~LinearAllocator();
+
+    /**
+     * Reserves and returns a region of memory of at least size 'size', aligning as needed.
+     * Typically this is used in an object's overridden new() method or as a replacement for malloc.
+     *
+     * The lifetime of the returned buffers is tied to that of the LinearAllocator. If calling
+     * delete() on an object stored in a buffer is needed, it should be overridden to use
+     * rewindIfLastAlloc()
+     */
+    void* alloc(size_t size);
+
+    /**
+     * Attempt to deallocate the given buffer, with the LinearAllocator attempting to rewind its
+     * state if possible. No destructors are called.
+     */
+    void rewindIfLastAlloc(void* ptr, size_t allocSize);
+
+    /**
+     * Dump memory usage statistics to the log (allocated and wasted space)
+     */
+    void dumpMemoryStats(const char* prefix = "");
+
+    /**
+     * The number of bytes used for buffers allocated in the LinearAllocator (does not count space
+     * wasted)
+     */
+    size_t usedSize() const { return mTotalAllocated - mWastedSpace; }
+
+private:
+    LinearAllocator(const LinearAllocator& other);
+
+    class Page;
+
+    Page* newPage(size_t pageSize);
+    bool fitsInCurrentPage(size_t size);
+    void ensureNext(size_t size);
+    void* start(Page *p);
+    void* end(Page* p);
+
+    size_t mPageSize;
+    size_t mMaxAllocSize;
+    void* mNext;
+    Page* mCurrentPage;
+    Page* mPages;
+
+    // Memory usage tracking
+    size_t mTotalAllocated;
+    size_t mWastedSpace;
+    size_t mPageCount;
+    size_t mDedicatedPageCount;
+};
+
+}; // namespace android
+
+#endif // ANDROID_LINEARALLOCATOR_H
-- 
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