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| /**
* Copyright 2017 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { Query } from '../core/query';
import { Timestamp } from '../core/timestamp';
import { BatchId, ProtoByteString } from '../core/types';
import { DocumentKey } from '../model/document_key';
import { Mutation } from '../model/mutation';
import { BATCHID_UNKNOWN, MutationBatch } from '../model/mutation_batch';
import { emptyByteString } from '../platform/platform';
import { assert } from '../util/assert';
import { primitiveComparator } from '../util/misc';
import { SortedSet } from '../util/sorted_set';
import { GarbageCollector } from './garbage_collector';
import { MutationQueue } from './mutation_queue';
import { PersistenceTransaction } from './persistence';
import { PersistencePromise } from './persistence_promise';
import { DocReference } from './reference_set';
export class MemoryMutationQueue implements MutationQueue {
/**
* The set of all mutations that have been sent but not yet been applied to
* the backend.
*/
private mutationQueue: MutationBatch[] = [];
/** Next value to use when assigning sequential IDs to each mutation batch. */
private nextBatchId: BatchId = 1;
/** The highest acknowledged mutation in the queue. */
private highestAcknowledgedBatchId: BatchId = BATCHID_UNKNOWN;
/** The last received stream token from the server, used to acknowledge which
* responses the client has processed. Stream tokens are opaque checkpoint
* markers whose only real value is their inclusion in the next request.
*/
private lastStreamToken: ProtoByteString = emptyByteString();
/** The garbage collector to notify about potential garbage keys. */
private garbageCollector: GarbageCollector | null = null;
/** An ordered mapping between documents and the mutations batch IDs. */
private batchesByDocumentKey = new SortedSet(DocReference.compareByKey);
start(transaction: PersistenceTransaction): PersistencePromise<void> {
// NOTE: The queue may be shutdown / started multiple times, since we
// maintain the queue for the duration of the app session in case a user
// logs out / back in. To behave like the LevelDB-backed MutationQueue (and
// accommodate tests that expect as much), we reset nextBatchId and
// highestAcknowledgedBatchId if the queue is empty.
if (this.mutationQueue.length === 0) {
this.nextBatchId = 1;
this.highestAcknowledgedBatchId = BATCHID_UNKNOWN;
}
assert(
this.highestAcknowledgedBatchId < this.nextBatchId,
'highestAcknowledgedBatchId must be less than the nextBatchId'
);
return PersistencePromise.resolve();
}
checkEmpty(transaction: PersistenceTransaction): PersistencePromise<boolean> {
return PersistencePromise.resolve(this.mutationQueue.length === 0);
}
getNextBatchId(
transaction: PersistenceTransaction
): PersistencePromise<BatchId> {
return PersistencePromise.resolve(this.nextBatchId);
}
getHighestAcknowledgedBatchId(
transaction: PersistenceTransaction
): PersistencePromise<BatchId> {
return PersistencePromise.resolve(this.highestAcknowledgedBatchId);
}
acknowledgeBatch(
transaction: PersistenceTransaction,
batch: MutationBatch,
streamToken: ProtoByteString
): PersistencePromise<void> {
const batchId = batch.batchId;
assert(
batchId > this.highestAcknowledgedBatchId,
'Mutation batchIDs must be acknowledged in order'
);
const batchIndex = this.indexOfExistingBatchId(batchId, 'acknowledged');
// Verify that the batch in the queue is the one to be acknowledged.
const check = this.mutationQueue[batchIndex];
assert(
batchId === check.batchId,
'Queue ordering failure: expected batch ' +
batchId +
', got batch ' +
check.batchId
);
assert(
!check.isTombstone(),
"Can't acknowledge a previously removed batch"
);
this.highestAcknowledgedBatchId = batchId;
this.lastStreamToken = streamToken;
return PersistencePromise.resolve();
}
getLastStreamToken(
transaction: PersistenceTransaction
): PersistencePromise<ProtoByteString> {
return PersistencePromise.resolve(this.lastStreamToken);
}
setLastStreamToken(
transaction: PersistenceTransaction,
streamToken: ProtoByteString
): PersistencePromise<void> {
this.lastStreamToken = streamToken;
return PersistencePromise.resolve();
}
addMutationBatch(
transaction: PersistenceTransaction,
localWriteTime: Timestamp,
mutations: Mutation[]
): PersistencePromise<MutationBatch> {
assert(mutations.length !== 0, 'Mutation batches should not be empty');
const batchId = this.nextBatchId;
this.nextBatchId++;
if (this.mutationQueue.length > 0) {
const prior = this.mutationQueue[this.mutationQueue.length - 1];
assert(
prior.batchId < batchId,
'Mutation batchIDs must be monotonically increasing order'
);
}
const batch = new MutationBatch(batchId, localWriteTime, mutations);
this.mutationQueue.push(batch);
// Track references by document key.
for (const mutation of mutations) {
this.batchesByDocumentKey = this.batchesByDocumentKey.add(
new DocReference(mutation.key, batchId)
);
}
return PersistencePromise.resolve(batch);
}
lookupMutationBatch(
transaction: PersistenceTransaction,
batchId: BatchId
): PersistencePromise<MutationBatch | null> {
return PersistencePromise.resolve(this.findMutationBatch(batchId));
}
getNextMutationBatchAfterBatchId(
transaction: PersistenceTransaction,
batchId: BatchId
): PersistencePromise<MutationBatch | null> {
const size = this.mutationQueue.length;
// All batches with batchId <= this.highestAcknowledgedBatchId have been
// acknowledged so the first unacknowledged batch after batchID will have a
// batchID larger than both of these values.
batchId = Math.max(batchId + 1, this.highestAcknowledgedBatchId);
// The requested batchId may still be out of range so normalize it to the
// start of the queue.
const rawIndex = this.indexOfBatchId(batchId);
let index = rawIndex < 0 ? 0 : rawIndex;
// Finally return the first non-tombstone batch.
for (; index < size; index++) {
const batch = this.mutationQueue[index];
if (!batch.isTombstone()) {
return PersistencePromise.resolve(batch);
}
}
return PersistencePromise.resolve(null);
}
getAllMutationBatches(
transaction: PersistenceTransaction
): PersistencePromise<MutationBatch[]> {
return PersistencePromise.resolve(
this.getAllLiveMutationBatchesBeforeIndex(this.mutationQueue.length)
);
}
getAllMutationBatchesThroughBatchId(
transaction: PersistenceTransaction,
batchId: BatchId
): PersistencePromise<MutationBatch[]> {
const count = this.mutationQueue.length;
let endIndex = this.indexOfBatchId(batchId);
if (endIndex < 0) {
endIndex = 0;
} else if (endIndex >= count) {
endIndex = count;
} else {
// The endIndex is in the queue so increment to pull everything in the
// queue including it.
endIndex++;
}
return PersistencePromise.resolve(
this.getAllLiveMutationBatchesBeforeIndex(endIndex)
);
}
getAllMutationBatchesAffectingDocumentKey(
transaction: PersistenceTransaction,
documentKey: DocumentKey
): PersistencePromise<MutationBatch[]> {
const start = new DocReference(documentKey, 0);
const end = new DocReference(documentKey, Number.POSITIVE_INFINITY);
const result: MutationBatch[] = [];
this.batchesByDocumentKey.forEachInRange([start, end], ref => {
assert(
documentKey.isEqual(ref.key),
"Should only iterate over a single key's batches"
);
const batch = this.findMutationBatch(ref.targetOrBatchId);
assert(
batch !== null,
'Batches in the index must exist in the main table'
);
result.push(batch!);
});
return PersistencePromise.resolve(result);
}
getAllMutationBatchesAffectingQuery(
transaction: PersistenceTransaction,
query: Query
): PersistencePromise<MutationBatch[]> {
// Use the query path as a prefix for testing if a document matches the
// query.
const prefix = query.path;
const immediateChildrenPathLength = prefix.length + 1;
// Construct a document reference for actually scanning the index. Unlike
// the prefix the document key in this reference must have an even number of
// segments. The empty segment can be used a suffix of the query path
// because it precedes all other segments in an ordered traversal.
let startPath = prefix;
Eif (!DocumentKey.isDocumentKey(startPath)) {
startPath = startPath.child('');
}
const start = new DocReference(new DocumentKey(startPath), 0);
// Find unique batchIDs referenced by all documents potentially matching the
// query.
let uniqueBatchIDs = new SortedSet<number>(primitiveComparator);
this.batchesByDocumentKey.forEachWhile(ref => {
const rowKeyPath = ref.key.path;
if (!prefix.isPrefixOf(rowKeyPath)) {
return false;
} else {
// Rows with document keys more than one segment longer than the query
// path can't be matches. For example, a query on 'rooms' can't match
// the document /rooms/abc/messages/xyx.
// TODO(mcg): we'll need a different scanner when we implement
// ancestor queries.
if (rowKeyPath.length === immediateChildrenPathLength) {
uniqueBatchIDs = uniqueBatchIDs.add(ref.targetOrBatchId);
}
return true;
}
}, start);
// Construct an array of matching batches, sorted by batchID to ensure that
// multiple mutations affecting the same document key are applied in order.
const result: MutationBatch[] = [];
uniqueBatchIDs.forEach(batchId => {
const batch = this.findMutationBatch(batchId);
Eif (batch !== null) {
result.push(batch);
}
});
return PersistencePromise.resolve(result);
}
removeMutationBatches(
transaction: PersistenceTransaction,
batches: MutationBatch[]
): PersistencePromise<void> {
const batchCount = batches.length;
assert(batchCount > 0, 'Should not remove mutations when none exist.');
const firstBatchId = batches[0].batchId;
const queueCount = this.mutationQueue.length;
// Find the position of the first batch for removal. This need not be the
// first entry in the queue.
const startIndex = this.indexOfExistingBatchId(firstBatchId, 'removed');
assert(
this.mutationQueue[startIndex].batchId === firstBatchId,
'Removed batches must exist in the queue'
);
// Check that removed batches are contiguous (while excluding tombstones).
let batchIndex = 1;
let queueIndex = startIndex + 1;
while (batchIndex < batchCount && queueIndex < queueCount) {
const batch = this.mutationQueue[queueIndex];
if (batch.isTombstone()) {
queueIndex++;
continue;
}
assert(
batch.batchId === batches[batchIndex].batchId,
'Removed batches must be contiguous in the queue'
);
batchIndex++;
queueIndex++;
}
// Only actually remove batches if removing at the front of the queue.
// Previously rejected batches may have left tombstones in the queue, so
// expand the removal range to include any tombstones.
if (startIndex === 0) {
for (; queueIndex < queueCount; queueIndex++) {
const batch = this.mutationQueue[queueIndex];
if (!batch.isTombstone()) {
break;
}
}
const length = queueIndex - startIndex;
this.mutationQueue.splice(startIndex, length);
} else {
// Mark the tombstones
for (let i = startIndex; i < queueIndex; i++) {
this.mutationQueue[i] = this.mutationQueue[i].toTombstone();
}
}
let references = this.batchesByDocumentKey;
for (const batch of batches) {
const batchId = batch.batchId;
for (const mutation of batch.mutations) {
const key = mutation.key;
if (this.garbageCollector !== null) {
this.garbageCollector.addPotentialGarbageKey(key);
}
const ref = new DocReference(key, batchId);
references = references.delete(ref);
}
}
this.batchesByDocumentKey = references;
return PersistencePromise.resolve();
}
setGarbageCollector(garbageCollector: GarbageCollector | null): void {
this.garbageCollector = garbageCollector;
}
containsKey(
txn: PersistenceTransaction,
key: DocumentKey
): PersistencePromise<boolean> {
const ref = new DocReference(key, 0);
const firstRef = this.batchesByDocumentKey.firstAfterOrEqual(ref);
return PersistencePromise.resolve(key.isEqual(firstRef && firstRef.key));
}
performConsistencyCheck(
txn: PersistenceTransaction
): PersistencePromise<void> {
if (this.mutationQueue.length === 0) {
assert(
this.batchesByDocumentKey.isEmpty(),
'Document leak -- detected dangling mutation references when queue is empty.'
);
}
return PersistencePromise.resolve();
}
/**
* A private helper that collects all the mutations batches in the queue up to
* but not including the given endIndex. All tombstones in the queue are
* excluded.
*/
private getAllLiveMutationBatchesBeforeIndex(
endIndex: number
): MutationBatch[] {
const result: MutationBatch[] = [];
for (let i = 0; i < endIndex; i++) {
const batch = this.mutationQueue[i];
if (!batch.isTombstone()) {
result.push(batch);
}
}
return result;
}
/**
* Finds the index of the given batchId in the mutation queue and asserts that
* the resulting index is within the bounds of the queue.
*
* @param batchId The batchId to search for
* @param action A description of what the caller is doing, phrased in passive
* form (e.g. "acknowledged" in a routine that acknowledges batches).
*/
private indexOfExistingBatchId(batchId: BatchId, action: string): number {
const index = this.indexOfBatchId(batchId);
assert(
index >= 0 && index < this.mutationQueue.length,
'Batches must exist to be ' + action
);
return index;
}
/**
* Finds the index of the given batchId in the mutation queue. This operation
* is O(1).
*
* @return The computed index of the batch with the given batchId, based on
* the state of the queue. Note this index can be negative if the requested
* batchId has already been remvoed from the queue or past the end of the
* queue if the batchId is larger than the last added batch.
*/
private indexOfBatchId(batchId: BatchId): number {
if (this.mutationQueue.length === 0) {
// As an index this is past the end of the queue
return 0;
}
// Examine the front of the queue to figure out the difference between the
// batchId and indexes in the array. Note that since the queue is ordered
// by batchId, if the first batch has a larger batchId then the requested
// batchId doesn't exist in the queue.
const firstBatchId = this.mutationQueue[0].batchId;
return batchId - firstBatchId;
}
/**
* A version of lookupMutationBatch that doesn't return a promise, this makes
* other functions that uses this code easier to read and more efficent.
*/
private findMutationBatch(batchId: BatchId): MutationBatch | null {
const index = this.indexOfBatchId(batchId);
if (index < 0 || index >= this.mutationQueue.length) {
return null;
}
const batch = this.mutationQueue[index];
assert(batch.batchId === batchId, 'If found batch must match');
return batch.isTombstone() ? null : batch;
}
}
|