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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
module leveldb.mojom;
import "components/filesystem/public/interfaces/directory.mojom";
import "mojo/common/unguessable_token.mojom";
enum DatabaseError {
OK,
NOT_FOUND,
CORRUPTION,
NOT_SUPPORTED,
INVALID_ARGUMENT,
IO_ERROR
};
enum BatchOperationType {
PUT_KEY,
DELETE_KEY,
DELETE_PREFIXED_KEY
};
struct BatchedOperation {
BatchOperationType type;
array<uint8> key;
array<uint8>? value;
};
struct KeyValue {
array<uint8> key;
array<uint8> value;
};
// Options which control the behavior of a database. (This struct corresponds
// with the struct in leveldb's options.h.)
struct OpenOptions {
// TODO(erg): Find all comparators and copy them into the service.
// If true, the database will be created if it is missing.
bool create_if_missing = false;
// If true, an error is raised if the database already exists.
bool error_if_exists = false;
// If true, the implementation will do aggressive checking of the
// data it is processing and will stop early if it detects any
// errors.
bool paranoid_checks = false;
// Default size is 4 megabytes.
uint64 write_buffer_size = 4194304;
// Number of open files that can be used by the DB. (Note: we globally set
// the default here to 80 instead of leveldb's default 1000 because we don't
// want to consume all file descriptors. See
// https://code.google.com/p/chromium/issues/detail?id=227313#c11 for
// details.)
int32 max_open_files = 80;
};
// Service which hands out databases.
interface LevelDBService {
// Open the database with the specified "name" in the specified "directory".
// Fails if the database doesn't already exist.
Open(filesystem.mojom.Directory directory,
string dbname,
associated LevelDBDatabase& database) => (DatabaseError status);
// Open the database with the specified "name" in the specified "directory".
OpenWithOptions(OpenOptions options,
filesystem.mojom.Directory directory,
string dbname,
associated LevelDBDatabase& database) => (DatabaseError status);
// Opens a database stored purely in memory.
OpenInMemory(associated LevelDBDatabase& database) => (DatabaseError status);
// Destroys the contents of the specified database. Returns OK if the database
// already didn't exist.
Destroy(filesystem.mojom.Directory directory,
string dbname) => (DatabaseError status);
};
// A leveldb database.
interface LevelDBDatabase {
// Basic Interface -------------------------------------------------------
// Sets the database entry for "key" to "value". Returns OK on success.
Put(array<uint8> key, array<uint8> value) => (DatabaseError status);
// 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.
Delete(array<uint8> key) => (DatabaseError status);
DeletePrefixed(array<uint8> key_prefix) => (DatabaseError status);
// Atomically performs all |operations|.
Write(array<BatchedOperation> operations) => (DatabaseError status);
Get(array<uint8> key) => (DatabaseError status, array<uint8> value);
GetPrefixed(array<uint8> key_prefix)
=> (DatabaseError status, array<KeyValue> data);
// Snapshots -------------------------------------------------------------
// Returns a handle to the current database state.
GetSnapshot() => (mojo.common.mojom.UnguessableToken snapshot);
// Releases a previously acquired snapshot.
ReleaseSnapshot(mojo.common.mojom.UnguessableToken snapshot);
// If |key| exists at the time |snapshot_id| was taken, return OK and the
// value. Otherwise return NOT_FOUND.
GetFromSnapshot(mojo.common.mojom.UnguessableToken snapshot,
array<uint8> key)
=> (DatabaseError status, array<uint8> value);
// Iteartors -------------------------------------------------------------
// Creates an iterator, either from the current view or from a snapshot.
NewIterator() => (mojo.common.mojom.UnguessableToken iterator);
NewIteratorFromSnapshot(mojo.common.mojom.UnguessableToken snapshot)
=> (mojo.common.mojom.UnguessableToken? iterator);
ReleaseIterator(mojo.common.mojom.UnguessableToken iterator);
// Positions the iterator at the first key, last key, or the first key after
// |target|.
[Sync]
IteratorSeekToFirst(mojo.common.mojom.UnguessableToken iterator)
=> (bool valid, DatabaseError status, array<uint8>? key,
array<uint8>? value);
[Sync]
IteratorSeekToLast(mojo.common.mojom.UnguessableToken iterator)
=> (bool valid, DatabaseError status, array<uint8>? key,
array<uint8>? value);
[Sync]
IteratorSeek(mojo.common.mojom.UnguessableToken iterator, array<uint8> target)
=> (bool valid, DatabaseError status, array<uint8>? key,
array<uint8>? value);
// Moves forward or backwards in iterator space.
[Sync]
IteratorNext(mojo.common.mojom.UnguessableToken iterator)
=> (bool valid, DatabaseError status, array<uint8>? key,
array<uint8>? value);
[Sync]
IteratorPrev(mojo.common.mojom.UnguessableToken iterator)
=> (bool valid, DatabaseError status, array<uint8>? key,
array<uint8>? value);
};
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