Add cache validation to ensure the validity
Create cache identity from GL_VERSION and store in ShaderCache.
In the next time ShaderCache is restored from disk, compare the
cache identity to ensure its validity. If GL_VERSION changes in
between, flush out entire FileBlobCache and start from an empty
one.
Bug: b/71800782
Test: Wrote a new unit test to save and restore ShaderCache
Test: hwui_unit_tests
Change-Id: Ie573dc4f18733eee090725be30445d879765231b
diff --git a/libs/hwui/pipeline/skia/ShaderCache.cpp b/libs/hwui/pipeline/skia/ShaderCache.cpp
index 6700748..073b481 100644
--- a/libs/hwui/pipeline/skia/ShaderCache.cpp
+++ b/libs/hwui/pipeline/skia/ShaderCache.cpp
@@ -18,6 +18,8 @@
#include <algorithm>
#include <log/log.h>
#include <thread>
+#include <array>
+#include <openssl/sha.h>
#include "FileBlobCache.h"
#include "Properties.h"
#include "utils/TraceUtils.h"
@@ -41,7 +43,40 @@
return sCache;
}
-void ShaderCache::initShaderDiskCache() {
+bool ShaderCache::validateCache(const void* identity, ssize_t size) {
+ if (nullptr == identity && size == 0)
+ return true;
+
+ if (nullptr == identity || size < 0) {
+ if (CC_UNLIKELY(Properties::debugLevel & kDebugCaches)) {
+ ALOGW("ShaderCache::validateCache invalid cache identity");
+ }
+ mBlobCache->clear();
+ return false;
+ }
+
+ SHA256_CTX ctx;
+ SHA256_Init(&ctx);
+
+ SHA256_Update(&ctx, identity, size);
+ mIDHash.resize(SHA256_DIGEST_LENGTH);
+ SHA256_Final(mIDHash.data(), &ctx);
+
+ std::array<uint8_t, SHA256_DIGEST_LENGTH> hash;
+ auto key = sIDKey;
+ auto loaded = mBlobCache->get(&key, sizeof(key), hash.data(), hash.size());
+
+ if (loaded && std::equal(hash.begin(), hash.end(), mIDHash.begin()))
+ return true;
+
+ if (CC_UNLIKELY(Properties::debugLevel & kDebugCaches)) {
+ ALOGW("ShaderCache::validateCache cache validation fails");
+ }
+ mBlobCache->clear();
+ return false;
+}
+
+void ShaderCache::initShaderDiskCache(const void* identity, ssize_t size) {
ATRACE_NAME("initShaderDiskCache");
std::lock_guard<std::mutex> lock(mMutex);
@@ -50,6 +85,7 @@
// desktop / laptop GPUs. Thus, disable the shader disk cache for emulator builds.
if (!Properties::runningInEmulator && mFilename.length() > 0) {
mBlobCache.reset(new FileBlobCache(maxKeySize, maxValueSize, maxTotalSize, mFilename));
+ validateCache(identity, size);
mInitialized = true;
}
}
@@ -104,6 +140,18 @@
return SkData::MakeFromMalloc(valueBuffer, valueSize);
}
+void ShaderCache::saveToDiskLocked() {
+ ATRACE_NAME("ShaderCache::saveToDiskLocked");
+ if (mInitialized && mBlobCache && mSavePending) {
+ if (mIDHash.size()) {
+ auto key = sIDKey;
+ mBlobCache->set(&key, sizeof(key), mIDHash.data(), mIDHash.size());
+ }
+ mBlobCache->writeToFile();
+ }
+ mSavePending = false;
+}
+
void ShaderCache::store(const SkData& key, const SkData& data) {
ATRACE_NAME("ShaderCache::store");
std::lock_guard<std::mutex> lock(mMutex);
@@ -129,11 +177,7 @@
std::thread deferredSaveThread([this]() {
sleep(mDeferredSaveDelay);
std::lock_guard<std::mutex> lock(mMutex);
- ATRACE_NAME("ShaderCache::saveToDisk");
- if (mInitialized && mBlobCache) {
- mBlobCache->writeToFile();
- }
- mSavePending = false;
+ saveToDiskLocked();
});
deferredSaveThread.detach();
}
diff --git a/libs/hwui/pipeline/skia/ShaderCache.h b/libs/hwui/pipeline/skia/ShaderCache.h
index 27473d6..82804cf 100644
--- a/libs/hwui/pipeline/skia/ShaderCache.h
+++ b/libs/hwui/pipeline/skia/ShaderCache.h
@@ -40,12 +40,21 @@
ANDROID_API static ShaderCache& get();
/**
- * "initShaderDiskCache" loads the serialized cache contents from disk and puts the ShaderCache
- * into an initialized state, such that it is able to insert and retrieve entries from the
- * cache. This should be called when HWUI pipeline is initialized. When not in the initialized
- * state the load and store methods will return without performing any cache operations.
+ * initShaderDiskCache" loads the serialized cache contents from disk,
+ * optionally checks that the on-disk cache matches a provided identity,
+ * and puts the ShaderCache into an initialized state, such that it is
+ * able to insert and retrieve entries from the cache. If identity is
+ * non-null and validation fails, the cache is initialized but contains
+ * no data. If size is less than zero, the cache is initilaized but
+ * contains no data.
+ *
+ * This should be called when HWUI pipeline is initialized. When not in
+ * the initialized state the load and store methods will return without
+ * performing any cache operations.
*/
- virtual void initShaderDiskCache();
+ virtual void initShaderDiskCache(const void *identity, ssize_t size);
+
+ virtual void initShaderDiskCache() { initShaderDiskCache(nullptr, 0); }
/**
* "setFilename" sets the name of the file that should be used to store
@@ -83,6 +92,19 @@
BlobCache* getBlobCacheLocked();
/**
+ * "validateCache" updates the cache to match the given identity. If the
+ * cache currently has the wrong identity, all entries in the cache are cleared.
+ */
+ bool validateCache(const void* identity, ssize_t size);
+
+ /**
+ * "saveToDiskLocked" attemps to save the current contents of the cache to
+ * disk. If the identity hash exists, we will insert the identity hash into
+ * the cache for next validation.
+ */
+ void saveToDiskLocked();
+
+ /**
* "mInitialized" indicates whether the ShaderCache is in the initialized
* state. It is initialized to false at construction time, and gets set to
* true when initialize is called.
@@ -111,6 +133,15 @@
std::string mFilename;
/**
+ * "mIDHash" is the current identity hash for the cache validation. It is
+ * initialized to an empty vector at construction time, and its content is
+ * generated in the call of the validateCache method. An empty vector
+ * indicates that cache validation is not performed, and the hash should
+ * not be stored on disk.
+ */
+ std::vector<uint8_t> mIDHash;
+
+ /**
* "mSavePending" indicates whether or not a deferred save operation is
* pending. Each time a key/value pair is inserted into the cache via
* load, a deferred save is initiated if one is not already pending.
@@ -140,6 +171,11 @@
*/
static ShaderCache sCache;
+ /**
+ * "sIDKey" is the cache key of the identity hash
+ */
+ static constexpr uint8_t sIDKey = 0;
+
friend class ShaderCacheTestUtils; //used for unit testing
};