sync with upstream @ 21409451

Check the NEWS file for details of what changed.

git-svn-id: https://leveldb.googlecode.com/svn/trunk@28 62dab493-f737-651d-591e-8d6aee1b9529

1 files changed, 35 insertions, 2 deletions

diff --git a/db/log_reader.h b/db/log_reader.h
index baf1475..61cc414 100644
--- a/db/log_reader.h
+++ b/db/log_reader.h
@@ -5,6 +5,8 @@
 #ifndef STORAGE_LEVELDB_DB_LOG_READER_H_
 #define STORAGE_LEVELDB_DB_LOG_READER_H_
 
+#include <stdint.h>
+
 #include "db/log_format.h"
 #include "leveldb/slice.h"
 #include "leveldb/status.h"
@@ -35,7 +37,11 @@ class Reader {
   // live while this Reader is in use.
   //
   // If "checksum" is true, verify checksums if available.
-  Reader(SequentialFile* file, Reporter* reporter, bool checksum);
+  //
+  // The Reader will start reading at the first record located at physical
+  // position >= initial_offset within the file.
+  Reader(SequentialFile* file, Reporter* reporter, bool checksum,
+         uint64_t initial_offset);
 
   ~Reader();
 
@@ -46,6 +52,11 @@ class Reader {
   // reader or the next mutation to *scratch.
   bool ReadRecord(Slice* record, std::string* scratch);
 
+  // Returns the physical offset of the last record returned by ReadRecord.
+  //
+  // Undefined before the first call to ReadRecord.
+  uint64_t LastRecordOffset();
+
  private:
   SequentialFile* const file_;
   Reporter* const reporter_;
@@ -54,15 +65,37 @@ class Reader {
   Slice buffer_;
   bool eof_;   // Last Read() indicated EOF by returning < kBlockSize
 
+  // Offset of the last record returned by ReadRecord.
+  uint64_t last_record_offset_;
+  // Offset of the first location past the end of buffer_.
+  uint64_t end_of_buffer_offset_;
+
+  // Offset at which to start looking for the first record to return
+  uint64_t const initial_offset_;
+
   // Extend record types with the following special values
   enum {
     kEof = kMaxRecordType + 1,
+    // Returned whenever we find an invalid physical record.
+    // Currently there are three situations in which this happens:
+    // * The record has an invalid CRC (ReadPhysicalRecord reports a drop)
+    // * The record is a 0-length record (No drop is reported)
+    // * The record is below constructor's initial_offset (No drop is reported)
     kBadRecord = kMaxRecordType + 2
   };
 
+  // Skips all blocks that are completely before "initial_offset_".
+  //
+  // Returns true on success. Handles reporting.
+  bool SkipToInitialBlock();
+
   // Return type, or one of the preceding special values
   unsigned int ReadPhysicalRecord(Slice* result);
-  void ReportDrop(size_t bytes, const char* reason);
+
+  // Reports dropped bytes to the reporter.
+  // buffer_ must be updated to remove the dropped bytes prior to invocation.
+  void ReportCorruption(size_t bytes, const char* reason);
+  void ReportDrop(size_t bytes, const Status& reason);
 
   // No copying allowed
   Reader(const Reader&);