Added Caching for PreProcessed PNGs

Added a cache management system for pre-processed PNG files
along with unit tests. The cache system will be used if
the --no-crunch flag is passed to AAPT during the package
phase. The cache can be updated by a call to 'aapt crunch'
(see usage statement). Also put in benchmarking code.

Change-Id: I58271fb2ee2f5f9075fd74d4ff6f15e7afabd05c

1 files changed, 104 insertions, 0 deletions

diff --git a/tools/aapt/CrunchCache.cpp b/tools/aapt/CrunchCache.cpp
new file mode 100644
index 0000000..c4cf6bc
--- /dev/null
+++ b/tools/aapt/CrunchCache.cpp
@@ -0,0 +1,104 @@
+//
+// Copyright 2011 The Android Open Source Project
+//
+// Implementation file for CrunchCache
+// This file defines functions laid out and documented in
+// CrunchCache.h
+
+#include <utils/Vector.h>
+#include <utils/String8.h>
+
+#include "DirectoryWalker.h"
+#include "FileFinder.h"
+#include "CacheUpdater.h"
+#include "CrunchCache.h"
+
+using namespace android;
+
+CrunchCache::CrunchCache(String8 sourcePath, String8 destPath, FileFinder* ff)
+    : mSourcePath(sourcePath), mDestPath(destPath), mSourceFiles(0), mDestFiles(0), mFileFinder(ff)
+{
+    // We initialize the default value to return to 0 so if a file doesn't exist
+    // then all files are automatically "newer" than it.
+
+    // Set file extensions to look for. Right now just pngs.
+    mExtensions.push(String8(".png"));
+
+    // Load files into our data members
+    loadFiles();
+}
+
+size_t CrunchCache::crunch(CacheUpdater* cu, bool forceOverwrite)
+{
+    size_t numFilesUpdated = 0;
+
+    // Iterate through the source files and compare to cache.
+    // After processing a file, remove it from the source files and
+    // from the dest files.
+    // We're done when we're out of files in source.
+    String8 relativePath;
+    while (mSourceFiles.size() > 0) {
+        // Get the full path to the source file, then convert to a c-string
+        // and offset our beginning pointer to the length of the sourcePath
+        // This efficiently strips the source directory prefix from our path.
+        // Also, String8 doesn't have a substring method so this is what we've
+        // got to work with.
+        const char* rPathPtr = mSourceFiles.keyAt(0).string()+mSourcePath.length();
+        // Strip leading slash if present
+        int offset = 0;
+        if (rPathPtr[0] == OS_PATH_SEPARATOR)
+            offset = 1;
+        relativePath = String8(rPathPtr + offset);
+
+        if (forceOverwrite || needsUpdating(relativePath)) {
+            cu->processImage(mSourcePath.appendPathCopy(relativePath),
+                             mDestPath.appendPathCopy(relativePath));
+            numFilesUpdated++;
+            // crunchFile(relativePath);
+        }
+        // Delete this file from the source files and (if it exists) from the
+        // dest files.
+        mSourceFiles.removeItemsAt(0);
+        mDestFiles.removeItem(mDestPath.appendPathCopy(relativePath));
+    }
+
+    // Iterate through what's left of destFiles and delete leftovers
+    while (mDestFiles.size() > 0) {
+        cu->deleteFile(mDestFiles.keyAt(0));
+        mDestFiles.removeItemsAt(0);
+    }
+
+    // Update our knowledge of the files cache
+    // both source and dest should be empty by now.
+    loadFiles();
+
+    return numFilesUpdated;
+}
+
+void CrunchCache::loadFiles()
+{
+    // Clear out our data structures to avoid putting in duplicates
+    mSourceFiles.clear();
+    mDestFiles.clear();
+
+    // Make a directory walker that points to the system.
+    DirectoryWalker* dw = new SystemDirectoryWalker();
+
+    // Load files in the source directory
+    mFileFinder->findFiles(mSourcePath, mExtensions, mSourceFiles,dw);
+
+    // Load files in the destination directory
+    mFileFinder->findFiles(mDestPath,mExtensions,mDestFiles,dw);
+
+    delete dw;
+}
+
+bool CrunchCache::needsUpdating(String8 relativePath) const
+{
+    // Retrieve modification dates for this file entry under the source and
+    // cache directory trees. The vectors will return a modification date of 0
+    // if the file doesn't exist.
+    time_t sourceDate = mSourceFiles.valueFor(mSourcePath.appendPathCopy(relativePath));
+    time_t destDate = mDestFiles.valueFor(mDestPath.appendPathCopy(relativePath));
+    return sourceDate > destDate;
+}
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