reverting disastrous MOE commit, returning to r21

git-svn-id: https://leveldb.googlecode.com/svn/trunk@23 62dab493-f737-651d-591e-8d6aee1b9529

1 files changed, 142 insertions, 0 deletions

diff --git a/include/leveldb/db.h b/include/leveldb/db.h
new file mode 100644
index 0000000..f18ded3
--- /dev/null
+++ b/include/leveldb/db.h
@@ -0,0 +1,142 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef STORAGE_LEVELDB_INCLUDE_DB_H_
+#define STORAGE_LEVELDB_INCLUDE_DB_H_
+
+#include <stdint.h>
+#include <stdio.h>
+#include "leveldb/iterator.h"
+#include "leveldb/options.h"
+
+namespace leveldb {
+
+static const int kMajorVersion = 1;
+static const int kMinorVersion = 1;
+
+struct Options;
+struct ReadOptions;
+struct WriteOptions;
+
+class Snapshot;
+class WriteBatch;
+
+// Some internal types.  Clients should ignore.
+class WriteBatchInternal;
+
+struct Range {
+  Slice start;
+  Slice limit;
+
+  Range(const Slice& s, const Slice& l) : start(s), limit(l) { }
+};
+
+// A DB is a persistent ordered map from keys to values.
+class DB {
+ public:
+  // Open the database with the specified "name".
+  // Stores a pointer to a heap-allocated database in *dbptr and returns
+  // OK on success.
+  // Stores NULL in *dbptr and returns a non-OK status on error.
+  // Caller should delete *dbptr when it is no longer needed.
+  static Status Open(const Options& options,
+                     const std::string& name,
+                     DB** dbptr);
+
+  DB() { }
+  virtual ~DB();
+
+  // Set the database entry for "key" to "value".  Returns OK on success,
+  // and a non-OK status on error.
+  // Note: consider setting options.sync = true.
+  virtual Status Put(const WriteOptions& options,
+                     const Slice& key,
+                     const Slice& value) = 0;
+
+  // Remove the database entry (if any) for "key".  Returns OK on
+  // success, and a non-OK status on error.  It is not an error if "key"
+  // did not exist in the database.
+  // Note: consider setting options.sync = true.
+  virtual Status Delete(const WriteOptions& options, const Slice& key) = 0;
+
+  // Apply the specified updates to the database.
+  // Returns OK on success, non-OK on failure.
+  // Note: consider setting options.sync = true.
+  virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0;
+
+  // If the database contains an entry for "key" store the
+  // corresponding value in *value and return OK.
+  //
+  // If there is no entry for "key" leave *value unchanged and return
+  // a status for which Status::IsNotFound() returns true.
+  //
+  // May return some other Status on an error.
+  virtual Status Get(const ReadOptions& options,
+                     const Slice& key, std::string* value) = 0;
+
+  // Return a heap-allocated iterator over the contents of the database.
+  // The result of NewIterator() is initially invalid (caller must
+  // call one of the Seek methods on the iterator before using it).
+  //
+  // Caller should delete the iterator when it is no longer needed.
+  // The returned iterator should be deleted before this db is deleted.
+  virtual Iterator* NewIterator(const ReadOptions& options) = 0;
+
+  // Return a handle to the current DB state.  Iterators created with
+  // this handle will all observe a stable snapshot of the current DB
+  // state.  The caller must call ReleaseSnapshot(result) when the
+  // snapshot is no longer needed.
+  virtual const Snapshot* GetSnapshot() = 0;
+
+  // Release a previously acquired snapshot.  The caller must not
+  // use "snapshot" after this call.
+  virtual void ReleaseSnapshot(const Snapshot* snapshot) = 0;
+
+  // DB implementations can export properties about their state
+  // via this method.  If "property" is a valid property understood by this
+  // DB implementation, fills "*value" with its current value and returns
+  // true.  Otherwise returns false.
+  //
+  //
+  // Valid property names include:
+  //
+  //  "leveldb.num-files-at-level<N>" - return the number of files at level <N>,
+  //     where <N> is an ASCII representation of a level number (e.g. "0").
+  //  "leveldb.stats" - returns a multi-line string that describes statistics
+  //     about the internal operation of the DB.
+  virtual bool GetProperty(const Slice& property, std::string* value) = 0;
+
+  // For each i in [0,n-1], store in "sizes[i]", the approximate
+  // file system space used by keys in "[range[i].start .. range[i].limit)".
+  //
+  // Note that the returned sizes measure file system space usage, so
+  // if the user data compresses by a factor of ten, the returned
+  // sizes will be one-tenth the size of the corresponding user data size.
+  //
+  // The results may not include the sizes of recently written data.
+  virtual void GetApproximateSizes(const Range* range, int n,
+                                   uint64_t* sizes) = 0;
+
+  // Possible extensions:
+  // (1) Add a method to compact a range of keys
+
+ private:
+  // No copying allowed
+  DB(const DB&);
+  void operator=(const DB&);
+};
+
+// Destroy the contents of the specified database.
+// Be very careful using this method.
+Status DestroyDB(const std::string& name, const Options& options);
+
+// If a DB cannot be opened, you may attempt to call this method to
+// resurrect as much of the contents of the database as possible.
+// Some data may be lost, so be careful when calling this function
+// on a database that contains important information.
+Status RepairDB(const std::string& dbname, const Options& options);
+
+}
+
+#endif  // STORAGE_LEVELDB_INCLUDE_DB_H_