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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 { SnapshotVersion } from '../core/snapshot_version';
import { Timestamp } from '../core/timestamp';
import { assert, fail } from '../util/assert';
import * as misc from '../util/misc';
import { Document, MaybeDocument, NoDocument } from './document';
import { DocumentKey } from './document_key';
import { FieldValue, ObjectValue, ServerTimestampValue } from './field_value';
import { FieldPath } from './path';
/**
* Provides a set of fields that can be used to partially patch a document.
* FieldMask is used in conjunction with ObjectValue.
* Examples:
* foo - Overwrites foo entirely with the provided value. If foo is not
* present in the companion ObjectValue, the field is deleted.
* foo.bar - Overwrites only the field bar of the object foo.
* If foo is not an object, foo is replaced with an object
* containing foo
*/
export class FieldMask {
constructor(readonly fields: FieldPath[]) {
// TODO(dimond): validation of FieldMask
}
isEqual(other: FieldMask): boolean {
return misc.arrayEquals(this.fields, other.fields);
}
}
/** Represents a transform within a TransformMutation. */
export interface TransformOperation {
isEqual(other: TransformOperation): boolean;
}
/** Transforms a value into a server-generated timestamp. */
export class ServerTimestampTransform implements TransformOperation {
private constructor() {}
static instance = new ServerTimestampTransform();
isEqual(other: TransformOperation): boolean {
return other instanceof ServerTimestampTransform;
}
}
/** A field path and the TransformOperation to perform upon it. */
export class FieldTransform {
constructor(
readonly field: FieldPath,
readonly transform: TransformOperation
) {}
isEqual(other: FieldTransform): boolean {
return (
this.field.isEqual(other.field) && this.transform.isEqual(other.transform)
);
}
}
/** The result of successfully applying a mutation to the backend. */
export class MutationResult {
constructor(
/**
* The version at which the mutation was committed or null for a delete.
*/
readonly version: SnapshotVersion | null,
/**
* The resulting fields returned from the backend after a
* TransformMutation has been committed. Contains one FieldValue for each
* FieldTransform that was in the mutation.
*
* Will be null if the mutation was not a TransformMutation.
*/
readonly transformResults: FieldValue[] | null
) {}
}
export enum MutationType {
Set,
Patch,
Transform,
Delete
}
/**
* Encodes a precondition for a mutation. This follows the model that the
* backend accepts with the special case of an explicit "empty" precondition
* (meaning no precondition).
*/
export class Precondition {
static readonly NONE = new Precondition();
private constructor(
readonly updateTime?: SnapshotVersion,
readonly exists?: boolean
) {
assert(
updateTime === undefined || exists === undefined,
'Precondition can specify "exists" or "updateTime" but not both'
);
}
/** Creates a new Precondition with an exists flag. */
static exists(exists: boolean) {
return new Precondition(undefined, exists);
}
/** Creates a new Precondition based on a version a document exists at. */
static updateTime(version: SnapshotVersion) {
return new Precondition(version);
}
/** Returns whether this Precondition is empty. */
get isNone(): boolean {
return this.updateTime === undefined && this.exists === undefined;
}
/**
* Returns true if the preconditions is valid for the given document
* (or null if no document is available).
*/
isValidFor(maybeDoc: MaybeDocument | null) {
Iif (this.updateTime !== undefined) {
return (
maybeDoc instanceof Document &&
maybeDoc.version.isEqual(this.updateTime)
);
} else if (this.exists !== undefined) {
Eif (this.exists) {
return maybeDoc instanceof Document;
} else {
return maybeDoc === null || maybeDoc instanceof NoDocument;
}
} else {
assert(this.isNone, 'Precondition should be empty');
return true;
}
}
isEqual(other: Precondition) {
return (
misc.equals(this.updateTime, other.updateTime) &&
this.exists === other.exists
);
}
}
/**
* A mutation describes a self-contained change to a document. Mutations can
* create, replace, delete, and update subsets of documents.
*
* Mutations not only act on the value of the document but also it version.
* In the case of Set, Patch, and Transform mutations we preserve the existing
* version. In the case of Delete mutations, we reset the version to 0.
*
* Here's the expected transition table.
*
* MUTATION APPLIED TO RESULTS IN
*
* SetMutation Document(v3) Document(v3)
* SetMutation NoDocument(v3) Document(v0)
* SetMutation null Document(v0)
* PatchMutation Document(v3) Document(v3)
* PatchMutation NoDocument(v3) NoDocument(v3)
* PatchMutation null null
* TransformMutation Document(v3) Document(v3)
* TransformMutation NoDocument(v3) NoDocument(v3)
* TransformMutation null null
* DeleteMutation Document(v3) NoDocument(v0)
* DeleteMutation NoDocument(v3) NoDocument(v0)
* DeleteMutation null NoDocument(v0)
*
* Note that TransformMutations don't create Documents (in the case of being
* applied to a NoDocument), even though they would on the backend. This is
* because the client always combines the TransformMutation with a SetMutation
* or PatchMutation and we only want to apply the transform if the prior
* mutation resulted in a Document (always true for a SetMutation, but not
* necessarily for a PatchMutation).
*
* ## Subclassing Notes
*
* Subclasses of Mutation need to implement applyToRemoteDocument() and
* applyToLocalView() to implement the actual behavior of applying the mutation
* to some source document.
*/
export abstract class Mutation {
readonly type: MutationType;
readonly key: DocumentKey;
readonly precondition: Precondition;
/**
* Applies this mutation to the given MaybeDocument or null for the purposes
* of computing a new remote document. Both the input and returned documents
* can be null.
*
* @param maybeDoc The document to mutate. The input document can be null if
* the client has no knowledge of the pre-mutation state of the document.
* @param mutationResult The result of applying the mutation from the backend.
* @return The mutated document. The returned document may be null, but only
* if maybeDoc was null and the mutation would not create a new document.
*/
abstract applyToRemoteDocument(
maybeDoc: MaybeDocument | null,
mutationResult: MutationResult
): MaybeDocument | null;
/**
* Applies this mutation to the given MaybeDocument or null for the purposes
* of computing the new local view of a document. Both the input and returned
* documents can be null.
*
* @param maybeDoc The document to mutate. The input document can be null if
* the client has no knowledge of the pre-mutation state of the document.
* @param baseDoc The state of the document prior to this mutation batch. The
* input document can be null if the client has no knowledge of the
* pre-mutation state of the document.
* @param localWriteTime A timestamp indicating the local write time of the
* batch this mutation is a part of.
* @return The mutated document. The returned document may be null, but only
* if maybeDoc was null and the mutation would not create a new document.
*/
abstract applyToLocalView(
maybeDoc: MaybeDocument | null,
baseDoc: MaybeDocument | null,
localWriteTime: Timestamp
): MaybeDocument | null;
abstract isEqual(other: Mutation): boolean;
protected verifyKeyMatches(maybeDoc: MaybeDocument | null): void {
if (maybeDoc != null) {
assert(
maybeDoc.key.isEqual(this.key),
'Can only apply a mutation to a document with the same key'
);
}
}
/**
* Returns the version from the given document for use as the result of a
* mutation. Mutations are defined to return the version of the base document
* only if it is an existing document. Deleted and unknown documents have a
* post-mutation version of SnapshotVersion.MIN.
*/
protected static getPostMutationVersion(
maybeDoc: MaybeDocument | null
): SnapshotVersion {
if (maybeDoc instanceof Document) {
return maybeDoc.version;
} else {
return SnapshotVersion.MIN;
}
}
}
/**
* A mutation that creates or replaces the document at the given key with the
* object value contents.
*/
export class SetMutation extends Mutation {
constructor(
readonly key: DocumentKey,
readonly value: ObjectValue,
readonly precondition: Precondition
) {
super();
}
readonly type: MutationType = MutationType.Set;
applyToRemoteDocument(
maybeDoc: MaybeDocument | null,
mutationResult: MutationResult
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
assert(
mutationResult.transformResults == null,
'Transform results received by SetMutation.'
);
// Unlike applyToLocalView, if we're applying a mutation to a remote
// document the server has accepted the mutation so the precondition must
// have held.
const version = Mutation.getPostMutationVersion(maybeDoc);
return new Document(this.key, version, this.value, {
hasLocalMutations: false
});
}
applyToLocalView(
maybeDoc: MaybeDocument | null,
baseDoc: MaybeDocument | null,
localWriteTime: Timestamp
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
Iif (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
const version = Mutation.getPostMutationVersion(maybeDoc);
return new Document(this.key, version, this.value, {
hasLocalMutations: true
});
}
isEqual(other: Mutation): boolean {
return (
other instanceof SetMutation &&
this.key.isEqual(other.key) &&
this.value.isEqual(other.value) &&
this.precondition.isEqual(other.precondition)
);
}
}
/**
* A mutation that modifies fields of the document at the given key with the
* given values. The values are applied through a field mask:
*
* * When a field is in both the mask and the values, the corresponding field
* is updated.
* * When a field is in neither the mask nor the values, the corresponding
* field is unmodified.
* * When a field is in the mask but not in the values, the corresponding field
* is deleted.
* * When a field is not in the mask but is in the values, the values map is
* ignored.
*/
export class PatchMutation extends Mutation {
constructor(
readonly key: DocumentKey,
readonly data: ObjectValue,
readonly fieldMask: FieldMask,
readonly precondition: Precondition
) {
super();
}
readonly type: MutationType = MutationType.Patch;
applyToRemoteDocument(
maybeDoc: MaybeDocument | null,
mutationResult: MutationResult
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
assert(
mutationResult.transformResults == null,
'Transform results received by PatchMutation.'
);
// TODO(mcg): Relax enforcement of this precondition
//
// We shouldn't actually enforce the precondition since it already passed on
// the backend, but we may not have a local version of the document to
// patch, so we use the precondition to prevent incorrectly putting a
// partial document into our cache.
if (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
const version = Mutation.getPostMutationVersion(maybeDoc);
const newData = this.patchDocument(maybeDoc);
return new Document(this.key, version, newData, {
hasLocalMutations: false
});
}
applyToLocalView(
maybeDoc: MaybeDocument | null,
baseDoc: MaybeDocument | null,
localWriteTime: Timestamp
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
if (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
const version = Mutation.getPostMutationVersion(maybeDoc);
const newData = this.patchDocument(maybeDoc);
return new Document(this.key, version, newData, {
hasLocalMutations: true
});
}
isEqual(other: Mutation): boolean {
return (
other instanceof PatchMutation &&
this.key.isEqual(other.key) &&
this.fieldMask.isEqual(other.fieldMask) &&
this.precondition.isEqual(other.precondition)
);
}
/**
* Patches the data of document if available or creates a new document. Note
* that this does not check whether or not the precondition of this patch
* holds.
*/
private patchDocument(maybeDoc: MaybeDocument | null): ObjectValue {
let data: ObjectValue;
if (maybeDoc instanceof Document) {
data = maybeDoc.data;
} else {
data = ObjectValue.EMPTY;
}
return this.patchObject(data);
}
private patchObject(data: ObjectValue): ObjectValue {
for (const fieldPath of this.fieldMask.fields) {
const newValue = this.data.field(fieldPath);
if (newValue !== undefined) {
data = data.set(fieldPath, newValue);
} else {
data = data.delete(fieldPath);
}
}
return data;
}
}
/**
* A mutation that modifies specific fields of the document with transform
* operations. Currently the only supported transform is a server timestamp, but
* IP Address, increment(n), etc. could be supported in the future.
*
* It is somewhat similar to a PatchMutation in that it patches specific fields
* and has no effect when applied to a null or NoDocument (see comment on
* Mutation for rationale).
*/
export class TransformMutation extends Mutation {
readonly type: MutationType = MutationType.Transform;
// NOTE: We set a precondition of exists: true as a safety-check, since we
// always combine TransformMutations with a SetMutation or PatchMutation which
// (if successful) should end up with an existing document.
readonly precondition = Precondition.exists(true);
constructor(
readonly key: DocumentKey,
readonly fieldTransforms: FieldTransform[]
) {
super();
}
applyToRemoteDocument(
maybeDoc: MaybeDocument | null,
mutationResult: MutationResult
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
assert(
mutationResult.transformResults != null,
'Transform results missing for TransformMutation.'
);
const transformResults = mutationResult.transformResults!;
// TODO(mcg): Relax enforcement of this precondition
//
// We shouldn't actually enforce the precondition since it already passed on
// the backend, but we may not have a local version of the document to
// patch, so we use the precondition to prevent incorrectly putting a
// partial document into our cache.
if (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
const doc = this.requireDocument(maybeDoc);
const newData = this.transformObject(doc.data, transformResults);
return new Document(this.key, doc.version, newData, {
hasLocalMutations: false
});
}
applyToLocalView(
maybeDoc: MaybeDocument | null,
baseDoc: MaybeDocument | null,
localWriteTime: Timestamp
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
if (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
const doc = this.requireDocument(maybeDoc);
const transformResults = this.localTransformResults(
localWriteTime,
baseDoc
);
const newData = this.transformObject(doc.data, transformResults);
return new Document(this.key, doc.version, newData, {
hasLocalMutations: true
});
}
isEqual(other: Mutation): boolean {
return (
other instanceof TransformMutation &&
this.key.isEqual(other.key) &&
misc.arrayEquals(this.fieldTransforms, other.fieldTransforms) &&
this.precondition.isEqual(other.precondition)
);
}
/**
* Asserts that the given MaybeDocument is actually a Document and verifies
* that it matches the key for this mutation. Since we only support
* transformations with precondition exists this method is guaranteed to be
* safe.
*/
private requireDocument(maybeDoc: MaybeDocument | null): Document {
assert(
maybeDoc instanceof Document,
'Unknown MaybeDocument type ' + maybeDoc
);
const doc = maybeDoc! as Document;
assert(
doc.key.isEqual(this.key),
'Can only transform a document with the same key'
);
return doc;
}
/**
* Creates a list of "transform results" (a transform result is a field value
* representing the result of applying a transform) for use when applying a
* TransformMutation locally.
*
* @param localWriteTime The local time of the transform mutation (used to
* generate ServerTimestampValues).
* @param baseDoc The document prior to applying this mutation batch.
* @return The transform results list.
*/
private localTransformResults(
localWriteTime: Timestamp,
baseDoc: MaybeDocument | null
): FieldValue[] {
const transformResults = [] as FieldValue[];
for (const fieldTransform of this.fieldTransforms) {
const transform = fieldTransform.transform;
Eif (transform instanceof ServerTimestampTransform) {
let previousValue: FieldValue | null = null;
if (baseDoc instanceof Document) {
previousValue = baseDoc.field(fieldTransform.field) || null;
}
transformResults.push(
new ServerTimestampValue(localWriteTime, previousValue)
);
} else {
return fail('Encountered unknown transform: ' + transform);
}
}
return transformResults;
}
private transformObject(
data: ObjectValue,
transformResults: FieldValue[]
): ObjectValue {
assert(
transformResults.length === this.fieldTransforms.length,
'TransformResults length mismatch.'
);
for (let i = 0; i < this.fieldTransforms.length; i++) {
const fieldTransform = this.fieldTransforms[i];
const transform = fieldTransform.transform;
const fieldPath = fieldTransform.field;
Eif (transform instanceof ServerTimestampTransform) {
data = data.set(fieldPath, transformResults[i]);
} else {
return fail('Encountered unknown transform: ' + transform);
}
}
return data;
}
}
/** A mutation that deletes the document at the given key. */
export class DeleteMutation extends Mutation {
constructor(readonly key: DocumentKey, readonly precondition: Precondition) {
super();
}
readonly type: MutationType = MutationType.Delete;
applyToRemoteDocument(
maybeDoc: MaybeDocument | null,
mutationResult: MutationResult
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
assert(
mutationResult.transformResults == null,
'Transform results received by DeleteMutation.'
);
// Unlike applyToLocalView, if we're applying a mutation to a remote
// document the server has accepted the mutation so the precondition must
// have held.
return new NoDocument(this.key, SnapshotVersion.MIN);
}
applyToLocalView(
maybeDoc: MaybeDocument | null,
baseDoc: MaybeDocument | null,
localWriteTime: Timestamp
): MaybeDocument | null {
this.verifyKeyMatches(maybeDoc);
Iif (!this.precondition.isValidFor(maybeDoc)) {
return maybeDoc;
}
if (maybeDoc) {
assert(
maybeDoc.key.isEqual(this.key),
'Can only apply mutation to document with same key'
);
}
return new NoDocument(this.key, SnapshotVersion.forDeletedDoc());
}
isEqual(other: Mutation): boolean {
return (
other instanceof DeleteMutation &&
this.key.isEqual(other.key) &&
this.precondition.isEqual(other.precondition)
);
}
}
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