Added --disk-cache option

This option enables disk cache. If SIZE is 0, the disk cache is
disabled. This feature caches the downloaded data in memory, which
grows to at most SIZE bytes. The cache storage is created for aria2
instance and shared by all downloads. The one advantage of the disk
cache is reduce the disk seek time because the data is written in
larger unit and it is reordered by the offset of the file. If the
underlying file is heavily fragmented it is not the case.

1 files changed, 142 insertions, 0 deletions

diff --git a/src/WrDiskCacheEntry.h b/src/WrDiskCacheEntry.h
new file mode 100644
index 00000000..b3b31f6b
--- /dev/null
+++ b/src/WrDiskCacheEntry.h
@@ -0,0 +1,142 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2012 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef D_WR_DISK_CACHE_ENTRY_H
+#define D_WR_DISK_CACHE_ENTRY_H
+
+#include "common.h"
+
+#include <set>
+
+#include "SharedHandle.h"
+#include "a2functional.h"
+#include "error_code.h"
+
+namespace aria2 {
+
+class DiskAdaptor;
+class WrDiskCache;
+
+class WrDiskCacheEntry {
+public:
+  struct DataCell {
+    // Where the data is going to be put in DiskAdaptor
+    int64_t goff;
+    // data must be len+offset bytes. Thus, the cached data is
+    // [data+offset, data+offset+len).
+    unsigned char *data;
+    size_t offset;
+    size_t len;
+    bool operator<(const DataCell& rhs) const
+    {
+      return goff < rhs.goff;
+    }
+  };
+
+  typedef std::set<DataCell*, DerefLess<DataCell*> > DataCellSet;
+
+  WrDiskCacheEntry(const SharedHandle<DiskAdaptor>& diskAdaptor);
+  ~WrDiskCacheEntry();
+
+  // Flushes the cached data to the disk and deletes them.
+  void writeToDisk();
+  // Deletes cached data without flushing to the disk.
+  void clear();
+
+  // Caches |dataCell|
+  bool cacheData(DataCell* dataCell);
+  size_t getSize() const
+  {
+    return size_;
+  }
+  void setSizeKey(size_t sizeKey)
+  {
+    sizeKey_ = sizeKey;
+  }
+  size_t getSizeKey() const
+  {
+    return sizeKey_;
+  }
+  void setLastUpdate(int64_t clock)
+  {
+    lastUpdate_ = clock;
+  }
+  int64_t getLastUpdate() const
+  {
+    return lastUpdate_;
+  }
+  bool operator<(const WrDiskCacheEntry& rhs) const
+  {
+    return sizeKey_ > rhs.sizeKey_ ||
+      (sizeKey_ == rhs.sizeKey_ && lastUpdate_ < rhs.lastUpdate_);
+  }
+
+  enum {
+    CACHE_ERR_SUCCESS,
+    CACHE_ERR_ERROR
+  };
+
+  int getError() const
+  {
+    return error_;
+  }
+  error_code::Value getErrorCode() const
+  {
+    return errorCode_;
+  }
+
+  const DataCellSet& getDataSet() const
+  {
+    return set_;
+  }
+private:
+  void deleteDataCells();
+
+  size_t sizeKey_;
+  int64_t lastUpdate_;
+
+  size_t size_;
+
+  DataCellSet set_;
+
+  int error_;
+  error_code::Value errorCode_;
+
+  SharedHandle<DiskAdaptor> diskAdaptor_;
+};
+
+} // namespace aria2
+
+#endif // D_WR_DISK_CACHE_ENTRY_H
+