Adds a modified copy of talk/base to webrtc/base. It is the first step in
migrating talk/base to webrtc/base.
BUG=N/A
R=niklas.enbom@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/17479005
git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@6129 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/base/diskcache.h b/base/diskcache.h
new file mode 100644
index 0000000..4ac1be1
--- /dev/null
+++ b/base/diskcache.h
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_DISKCACHE_H__
+#define WEBRTC_BASE_DISKCACHE_H__
+
+#include <map>
+#include <string>
+
+#if defined(WEBRTC_WIN)
+#undef UnlockResource
+#endif // WEBRTC_WIN
+
+namespace rtc {
+
+class StreamInterface;
+
+///////////////////////////////////////////////////////////////////////////////
+// DiskCache - An LRU cache of streams, stored on disk.
+//
+// Streams are identified by a unique resource id. Multiple streams can be
+// associated with each resource id, distinguished by an index. When old
+// resources are flushed from the cache, all streams associated with those
+// resources are removed together.
+// DiskCache is designed to persist across executions of the program. It is
+// safe for use from an arbitrary number of users on a single thread, but not
+// from multiple threads or other processes.
+///////////////////////////////////////////////////////////////////////////////
+
+class DiskCache {
+public:
+ DiskCache();
+ virtual ~DiskCache();
+
+ bool Initialize(const std::string& folder, size_t size);
+ bool Purge();
+
+ bool LockResource(const std::string& id);
+ StreamInterface* WriteResource(const std::string& id, size_t index);
+ bool UnlockResource(const std::string& id);
+
+ StreamInterface* ReadResource(const std::string& id, size_t index) const;
+
+ bool HasResource(const std::string& id) const;
+ bool HasResourceStream(const std::string& id, size_t index) const;
+ bool DeleteResource(const std::string& id);
+
+ protected:
+ virtual bool InitializeEntries() = 0;
+ virtual bool PurgeFiles() = 0;
+
+ virtual bool FileExists(const std::string& filename) const = 0;
+ virtual bool DeleteFile(const std::string& filename) const = 0;
+
+ enum LockState { LS_UNLOCKED, LS_LOCKED, LS_UNLOCKING };
+ struct Entry {
+ LockState lock_state;
+ mutable size_t accessors;
+ size_t size;
+ size_t streams;
+ time_t last_modified;
+ };
+ typedef std::map<std::string, Entry> EntryMap;
+ friend class DiskCacheAdapter;
+
+ bool CheckLimit();
+
+ std::string IdToFilename(const std::string& id, size_t index) const;
+ bool FilenameToId(const std::string& filename, std::string* id,
+ size_t* index) const;
+
+ const Entry* GetEntry(const std::string& id) const {
+ return const_cast<DiskCache*>(this)->GetOrCreateEntry(id, false);
+ }
+ Entry* GetOrCreateEntry(const std::string& id, bool create);
+
+ void ReleaseResource(const std::string& id, size_t index) const;
+
+ std::string folder_;
+ size_t max_cache_, total_size_;
+ EntryMap map_;
+ mutable size_t total_accessors_;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// CacheLock - Automatically manage locking and unlocking, with optional
+// rollback semantics
+///////////////////////////////////////////////////////////////////////////////
+
+class CacheLock {
+public:
+ CacheLock(DiskCache* cache, const std::string& id, bool rollback = false)
+ : cache_(cache), id_(id), rollback_(rollback)
+ {
+ locked_ = cache_->LockResource(id_);
+ }
+ ~CacheLock() {
+ if (locked_) {
+ cache_->UnlockResource(id_);
+ if (rollback_) {
+ cache_->DeleteResource(id_);
+ }
+ }
+ }
+ bool IsLocked() const { return locked_; }
+ void Commit() { rollback_ = false; }
+
+private:
+ DiskCache* cache_;
+ std::string id_;
+ bool rollback_, locked_;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+} // namespace rtc
+
+#endif // WEBRTC_BASE_DISKCACHE_H__