EGL: implement loading and saving the cache

This change adds support for saving and loading the contents of the EGL
cache.  It also adds some simple tests for the EGL cache.

Change-Id: I18e5e789e0897a0783d29d1c1e64d26de2dd44c4

Author: Jamie Gennis

opengl/libs/EGL/egl_cache.cpp

@@ -19,11 +19,21 @@
 #include "egl_impl.h"
 #include "egldefs.h"
 
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
 // Cache size limits.
 static const size_t maxKeySize = 1024;
 static const size_t maxValueSize = 4096;
 static const size_t maxTotalSize = 64 * 1024;
 
+// Cache file header
+static const char* cacheFileMagic = "EGL$";
+static const size_t cacheFileHeaderSize = 8;
+
 // ----------------------------------------------------------------------------
 namespace android {
 // ----------------------------------------------------------------------------
@@ -54,9 +64,10 @@ egl_cache_t::egl_cache_t() :
 egl_cache_t::~egl_cache_t() {
 }
 
+egl_cache_t egl_cache_t::sCache;
+
 egl_cache_t* egl_cache_t::get() {
-    static egl_cache_t theCache;
-    return &theCache;
+    return &sCache;
 }
 
 void egl_cache_t::initialize(egl_display_t *display) {
@@ -136,6 +147,11 @@ EGLsizei egl_cache_t::getBlob(const void* key, EGLsizei keySize, void* value,
     return 0;
 }
 
+void egl_cache_t::setCacheFilename(const char* filename) {
+    Mutex::Autolock lock(mMutex);
+    mFilename = filename;
+}
+
 sp<BlobCache> egl_cache_t::getBlobCacheLocked() {
     if (mBlobCache == NULL) {
         mBlobCache = new BlobCache(maxKeySize, maxValueSize, maxTotalSize);
@@ -144,10 +160,154 @@ sp<BlobCache> egl_cache_t::getBlobCacheLocked() {
     return mBlobCache;
 }
 
+static uint32_t crc32c(const uint8_t* buf, size_t len) {
+    const uint32_t polyBits = 0x82F63B78;
+    uint32_t r = 0;
+    for (size_t i = 0; i < len; i++) {
+        r ^= buf[i];
+        for (int j = 0; j < 8; j++) {
+            if (r & 1) {
+                r = (r >> 1) ^ polyBits;
+            } else {
+                r >>= 1;
+            }
+        }
+    }
+    return r;
+}
+
 void egl_cache_t::saveBlobCacheLocked() {
+    if (mFilename.length() > 0) {
+        size_t cacheSize = mBlobCache->getFlattenedSize();
+        size_t headerSize = cacheFileHeaderSize;
+        const char* fname = mFilename.string();
+
+        // Try to create the file with no permissions so we can write it
+        // without anyone trying to read it.
+        int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0);
+        if (fd == -1) {
+            if (errno == EEXIST) {
+                // The file exists, delete it and try again.
+                if (unlink(fname) == -1) {
+                    // No point in retrying if the unlink failed.
+                    LOGE("error unlinking cache file %s: %s (%d)", fname,
+                            strerror(errno), errno);
+                    return;
+                }
+                // Retry now that we've unlinked the file.
+                fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0);
+            }
+            if (fd == -1) {
+                LOGE("error creating cache file %s: %s (%d)", fname,
+                        strerror(errno), errno);
+                return;
+            }
+        }
+
+        size_t fileSize = headerSize + cacheSize;
+        if (ftruncate(fd, fileSize) == -1) {
+            LOGE("error setting cache file size: %s (%d)", strerror(errno),
+                    errno);
+            close(fd);
+            unlink(fname);
+            return;
+        }
+
+        uint8_t* buf = reinterpret_cast<uint8_t*>(mmap(NULL, fileSize,
+                PROT_WRITE, MAP_SHARED, fd, 0));
+        if (buf == MAP_FAILED) {
+            LOGE("error mmaping cache file: %s (%d)", strerror(errno),
+                    errno);
+            close(fd);
+            unlink(fname);
+            return;
+        }
+
+        status_t err = mBlobCache->flatten(buf + headerSize, cacheSize, NULL,
+                0);
+        if (err != OK) {
+            LOGE("error writing cache contents: %s (%d)", strerror(-err),
+                    -err);
+            munmap(buf, fileSize);
+            close(fd);
+            unlink(fname);
+            return;
+        }
+
+        // Write the file magic and CRC
+        memcpy(buf, cacheFileMagic, 4);
+        uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4);
+        *crc = crc32c(buf + headerSize, cacheSize);
+
+        munmap(buf, fileSize);
+        fchmod(fd, S_IRUSR);
+        close(fd);
+    }
 }
 
 void egl_cache_t::loadBlobCacheLocked() {
+    if (mFilename.length() > 0) {
+        size_t headerSize = cacheFileHeaderSize;
+
+        int fd = open(mFilename.string(), O_RDONLY, 0);
+        if (fd == -1) {
+            if (errno != ENOENT) {
+                LOGE("error opening cache file %s: %s (%d)", mFilename.string(),
+                        strerror(errno), errno);
+            }
+            return;
+        }
+
+        struct stat statBuf;
+        if (fstat(fd, &statBuf) == -1) {
+            LOGE("error stat'ing cache file: %s (%d)", strerror(errno), errno);
+            close(fd);
+            return;
+        }
+
+        // Sanity check the size before trying to mmap it.
+        size_t fileSize = statBuf.st_size;
+        if (fileSize > maxTotalSize * 2) {
+            LOGE("cache file is too large: %#llx", statBuf.st_size);
+            close(fd);
+            return;
+        }
+
+        uint8_t* buf = reinterpret_cast<uint8_t*>(mmap(NULL, fileSize,
+                PROT_READ, MAP_PRIVATE, fd, 0));
+        if (buf == MAP_FAILED) {
+            LOGE("error mmaping cache file: %s (%d)", strerror(errno),
+                    errno);
+            close(fd);
+            return;
+        }
+
+        // Check the file magic and CRC
+        size_t cacheSize = fileSize - headerSize;
+        if (memcmp(buf, cacheFileMagic, 4) != 0) {
+            LOGE("cache file has bad mojo");
+            close(fd);
+            return;
+        }
+        uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4);
+        if (crc32c(buf + headerSize, cacheSize) != *crc) {
+            LOGE("cache file failed CRC check");
+            close(fd);
+            return;
+        }
+
+        status_t err = mBlobCache->unflatten(buf + headerSize, cacheSize, NULL, 0);
+        if (err != OK) {
+            LOGE("error reading cache contents: %s (%d)", strerror(-err),
+                    -err);
+            munmap(buf, fileSize);
+            close(fd);
+            return;
+        }
+
+        munmap(buf, fileSize);
+        close(fd);
+    }
 }
 
 // ----------------------------------------------------------------------------

opengl/libs/EGL/egl_cache.h

@@ -21,6 +21,7 @@
 #include <EGL/eglext.h>
 
 #include <utils/BlobCache.h>
+#include <utils/String8.h>
 #include <utils/StrongPointer.h>
 
 // ----------------------------------------------------------------------------
@@ -29,7 +30,7 @@ namespace android {
 
 class egl_display_t;
 
-class egl_cache_t {
+class EGLAPI egl_cache_t {
 public:
 
     // get returns a pointer to the singleton egl_cache_t object.  This
@@ -60,6 +61,10 @@ class egl_cache_t {
     EGLsizei getBlob(const void* key, EGLsizei keySize, void* value,
         EGLsizei valueSize);
 
+    // setCacheFilename sets the name of the file that should be used to store
+    // cache contents from one program invocation to another.
+    void setCacheFilename(const char* filename);
+
 private:
     // Creation and (the lack of) destruction is handled internally.
     egl_cache_t();
@@ -96,9 +101,19 @@ class egl_cache_t {
     // first time it's needed.
     sp<BlobCache> mBlobCache;
 
+    // mFilename is the name of the file for storing cache contents in between
+    // program invocations.  It is initialized to an empty string at
+    // construction time, and can be set with the setCacheFilename method.  An
+    // empty string indicates that the cache should not be saved to or restored
+    // from disk.
+    String8 mFilename;
+
     // mMutex is the mutex used to prevent concurrent access to the member
     // variables. It must be locked whenever the member variables are accessed.
     mutable Mutex mMutex;
+
+    // sCache is the singleton egl_cache_t object.
+    static egl_cache_t sCache;
 };
 
 // ----------------------------------------------------------------------------

opengl/libs/EGL/egl_display.h

@@ -59,7 +59,7 @@ struct egl_config_t {
 
 // ----------------------------------------------------------------------------
 
-class egl_display_t {
+class EGLAPI egl_display_t { // marked as EGLAPI for testing purposes
     static egl_display_t sDisplay[NUM_DISPLAYS];
     EGLDisplay getDisplay(EGLNativeDisplayType display);
 
@@ -141,4 +141,3 @@ EGLBoolean validate_display_surface(EGLDisplay dpy, EGLSurface surface);
 // ----------------------------------------------------------------------------
 
 #endif // ANDROID_EGL_DISPLAY_H
-

opengl/tests/EGLTest/Android.mk

@@ -7,6 +7,7 @@ LOCAL_MODULE := EGL_test
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_SRC_FILES := \
+    egl_cache_test.cpp \
     EGL_test.cpp \
 
 LOCAL_SHARED_LIBRARIES := \
@@ -21,9 +22,12 @@ LOCAL_STATIC_LIBRARIES := \
 
 LOCAL_C_INCLUDES := \
     bionic \
+    bionic/libc/private \
     bionic/libstdc++/include \
     external/gtest/include \
     external/stlport/stlport \
+    frameworks/base/opengl/libs \
+    frameworks/base/opengl/libs/EGL \
 
 include $(BUILD_EXECUTABLE)
 

opengl/tests/EGLTest/egl_cache_test.cpp

@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "EGL_test"
+//#define LOG_NDEBUG 0
+
+#include <gtest/gtest.h>
+
+#include <utils/Log.h>
+
+#include "egl_cache.h"
+#include "egl_display.h"
+
+namespace android {
+
+class EGLCacheTest : public ::testing::Test {
+protected:
+    virtual void SetUp() {
+        mCache = egl_cache_t::get();
+    }
+
+    virtual void TearDown() {
+        mCache->setCacheFilename("");
+        mCache->terminate();
+    }
+
+    egl_cache_t* mCache;
+};
+
+TEST_F(EGLCacheTest, UninitializedCacheAlwaysMisses) {
+    char buf[4] = { 0xee, 0xee, 0xee, 0xee };
+    mCache->setBlob("abcd", 4, "efgh", 4);
+    ASSERT_EQ(0, mCache->getBlob("abcd", 4, buf, 4));
+    ASSERT_EQ(0xee, buf[0]);
+    ASSERT_EQ(0xee, buf[1]);
+    ASSERT_EQ(0xee, buf[2]);
+    ASSERT_EQ(0xee, buf[3]);
+}
+
+TEST_F(EGLCacheTest, InitializedCacheAlwaysHits) {
+    char buf[4] = { 0xee, 0xee, 0xee, 0xee };
+    mCache->initialize(egl_display_t::get(EGL_DEFAULT_DISPLAY));
+    mCache->setBlob("abcd", 4, "efgh", 4);
+    ASSERT_EQ(4, mCache->getBlob("abcd", 4, buf, 4));
+    ASSERT_EQ('e', buf[0]);
+    ASSERT_EQ('f', buf[1]);
+    ASSERT_EQ('g', buf[2]);
+    ASSERT_EQ('h', buf[3]);
+}
+
+TEST_F(EGLCacheTest, TerminatedCacheAlwaysMisses) {
+    char buf[4] = { 0xee, 0xee, 0xee, 0xee };
+    mCache->initialize(egl_display_t::get(EGL_DEFAULT_DISPLAY));
+    mCache->setBlob("abcd", 4, "efgh", 4);
+    mCache->terminate();
+    ASSERT_EQ(0, mCache->getBlob("abcd", 4, buf, 4));
+    ASSERT_EQ(0xee, buf[0]);
+    ASSERT_EQ(0xee, buf[1]);
+    ASSERT_EQ(0xee, buf[2]);
+    ASSERT_EQ(0xee, buf[3]);
+}
+
+class EGLCacheSerializationTest : public EGLCacheTest {
+
+protected:
+
+    virtual void SetUp() {
+        EGLCacheTest::SetUp();
+
+        char* tn = tempnam("/sdcard", "EGL_test-cache-");
+        mFilename = tn;
+        free(tn);
+    }
+
+    virtual void TearDown() {
+        unlink(mFilename.string());
+        EGLCacheTest::TearDown();
+    }
+
+    String8 mFilename;
+};
+
+TEST_F(EGLCacheSerializationTest, ReinitializedCacheContainsValues) {
+    char buf[4] = { 0xee, 0xee, 0xee, 0xee };
+    mCache->setCacheFilename(mFilename);
+    mCache->initialize(egl_display_t::get(EGL_DEFAULT_DISPLAY));
+    mCache->setBlob("abcd", 4, "efgh", 4);
+    mCache->terminate();
+    mCache->initialize(egl_display_t::get(EGL_DEFAULT_DISPLAY));
+    ASSERT_EQ(4, mCache->getBlob("abcd", 4, buf, 4));
+    ASSERT_EQ('e', buf[0]);
+    ASSERT_EQ('f', buf[1]);
+    ASSERT_EQ('g', buf[2]);
+    ASSERT_EQ('h', buf[3]);
+}
+
+}