mongodb
Version:
The official MongoDB driver for Node.js
294 lines • 14 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.DeprioritizedServers = exports.MIN_SECONDARY_WRITE_WIRE_VERSION = void 0;
exports.writableServerSelector = writableServerSelector;
exports.sameServerSelector = sameServerSelector;
exports.secondaryWritableServerSelector = secondaryWritableServerSelector;
exports.readPreferenceServerSelector = readPreferenceServerSelector;
const error_1 = require("../error");
const read_preference_1 = require("../read_preference");
const common_1 = require("./common");
// max staleness constants
const IDLE_WRITE_PERIOD = 10000;
const SMALLEST_MAX_STALENESS_SECONDS = 90;
// Minimum version to try writes on secondaries.
exports.MIN_SECONDARY_WRITE_WIRE_VERSION = 13;
/** @internal */
class DeprioritizedServers {
constructor(descriptions) {
this.deprioritized = new Set();
for (const description of descriptions ?? []) {
this.add(description);
}
}
add({ address }) {
this.deprioritized.add(address);
}
has({ address }) {
return this.deprioritized.has(address);
}
}
exports.DeprioritizedServers = DeprioritizedServers;
function filterDeprioritized(candidates, deprioritized) {
const filtered = candidates.filter(candidate => !deprioritized.has(candidate));
return filtered.length ? filtered : candidates;
}
/**
* Returns a server selector that selects for writable servers
*/
function writableServerSelector() {
return function writableServer(topologyDescription, servers, deprioritized) {
const eligibleServers = filterDeprioritized(servers.filter(({ isWritable }) => isWritable), deprioritized);
return latencyWindowReducer(topologyDescription, eligibleServers);
};
}
/**
* The purpose of this selector is to select the same server, only
* if it is in a state that it can have commands sent to it.
*/
function sameServerSelector(description) {
return function sameServerSelector(_topologyDescription, servers, _deprioritized) {
if (!description)
return [];
// Filter the servers to match the provided description only if
// the type is not unknown.
return servers.filter(sd => {
return sd.address === description.address && sd.type !== common_1.ServerType.Unknown;
});
};
}
/**
* Returns a server selector that uses a read preference to select a
* server potentially for a write on a secondary.
*/
function secondaryWritableServerSelector(wireVersion, readPreference) {
// If server version < 5.0, read preference always primary.
// If server version >= 5.0...
// - If read preference is supplied, use that.
// - If no read preference is supplied, use primary.
if (!readPreference ||
!wireVersion ||
(wireVersion && wireVersion < exports.MIN_SECONDARY_WRITE_WIRE_VERSION)) {
return readPreferenceServerSelector(read_preference_1.ReadPreference.primary);
}
return readPreferenceServerSelector(readPreference);
}
/**
* Reduces the passed in array of servers by the rules of the "Max Staleness" specification
* found here:
*
* @see https://github.com/mongodb/specifications/blob/master/source/max-staleness/max-staleness.md
*
* @param readPreference - The read preference providing max staleness guidance
* @param topologyDescription - The topology description
* @param servers - The list of server descriptions to be reduced
* @returns The list of servers that satisfy the requirements of max staleness
*/
function maxStalenessReducer(readPreference, topologyDescription, servers) {
if (readPreference.maxStalenessSeconds == null || readPreference.maxStalenessSeconds < 0) {
return servers;
}
const maxStaleness = readPreference.maxStalenessSeconds;
const maxStalenessVariance = (topologyDescription.heartbeatFrequencyMS + IDLE_WRITE_PERIOD) / 1000;
if (maxStaleness < maxStalenessVariance) {
throw new error_1.MongoInvalidArgumentError(`Option "maxStalenessSeconds" must be at least ${maxStalenessVariance} seconds`);
}
if (maxStaleness < SMALLEST_MAX_STALENESS_SECONDS) {
throw new error_1.MongoInvalidArgumentError(`Option "maxStalenessSeconds" must be at least ${SMALLEST_MAX_STALENESS_SECONDS} seconds`);
}
if (topologyDescription.type === common_1.TopologyType.ReplicaSetWithPrimary) {
const primary = Array.from(topologyDescription.servers.values()).filter(primaryFilter)[0];
return servers.filter((server) => {
const stalenessMS = server.lastUpdateTime -
server.lastWriteDate -
(primary.lastUpdateTime - primary.lastWriteDate) +
topologyDescription.heartbeatFrequencyMS;
const staleness = stalenessMS / 1000;
const maxStalenessSeconds = readPreference.maxStalenessSeconds ?? 0;
return staleness <= maxStalenessSeconds;
});
}
if (topologyDescription.type === common_1.TopologyType.ReplicaSetNoPrimary) {
if (servers.length === 0) {
return servers;
}
const sMax = servers.reduce((max, s) => s.lastWriteDate > max.lastWriteDate ? s : max);
return servers.filter((server) => {
const stalenessMS = sMax.lastWriteDate - server.lastWriteDate + topologyDescription.heartbeatFrequencyMS;
const staleness = stalenessMS / 1000;
const maxStalenessSeconds = readPreference.maxStalenessSeconds ?? 0;
return staleness <= maxStalenessSeconds;
});
}
return servers;
}
/**
* Determines whether a server's tags match a given set of tags.
*
* A tagset matches the server's tags if every k-v pair in the tagset
* is also in the server's tagset.
*
* Note that this does not requires that every k-v pair in the server's tagset is also
* in the client's tagset. The server's tagset is required only to be a superset of the
* client's tags.
*
* @see https://github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.md#tag_sets
*
* @param tagSet - The requested tag set to match
* @param serverTags - The server's tags
*/
function tagSetMatch(tagSet, serverTags) {
return Object.entries(tagSet).every(([key, value]) => serverTags[key] != null && serverTags[key] === value);
}
/**
* Reduces a set of server descriptions based on tags requested by the read preference
*
* @param readPreference - The read preference providing the requested tags
* @param servers - The list of server descriptions to reduce
* @returns The list of servers matching the requested tags
*/
function tagSetReducer({ tags }, servers) {
if (tags == null || tags.length === 0) {
// empty tag sets match all servers
return servers;
}
for (const tagSet of tags) {
const serversMatchingTagset = servers.filter((s) => tagSetMatch(tagSet, s.tags));
if (serversMatchingTagset.length) {
return serversMatchingTagset;
}
}
return [];
}
/**
* Reduces a list of servers to ensure they fall within an acceptable latency window. This is
* further specified in the "Server Selection" specification, found here:
*
* @see https://github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.md
*
* @param topologyDescription - The topology description
* @param servers - The list of servers to reduce
* @returns The servers which fall within an acceptable latency window
*/
function latencyWindowReducer(topologyDescription, servers) {
const low = servers.reduce((min, server) => Math.min(server.roundTripTime, min), Infinity);
const high = low + topologyDescription.localThresholdMS;
return servers.filter(server => server.roundTripTime <= high && server.roundTripTime >= low);
}
// filters
function primaryFilter(server) {
return server.type === common_1.ServerType.RSPrimary;
}
function secondaryFilter(server) {
return server.type === common_1.ServerType.RSSecondary;
}
function nearestFilter(server) {
return server.type === common_1.ServerType.RSSecondary || server.type === common_1.ServerType.RSPrimary;
}
function knownFilter(server) {
return server.type !== common_1.ServerType.Unknown;
}
function loadBalancerFilter(server) {
return server.type === common_1.ServerType.LoadBalancer;
}
function isDeprioritizedFactory(deprioritized) {
return server =>
// if any deprioritized servers equal the server, here we are.
!deprioritized.has(server);
}
function secondarySelector(readPreference, topologyDescription, servers, deprioritized) {
const mode = readPreference.mode;
switch (mode) {
case 'primary':
// Note: no need to filter for deprioritized servers. A replica set has only one primary; that means that
// we are in one of two scenarios:
// 1. deprioritized servers is empty - return the primary.
// 2. deprioritized servers contains the primary - return the primary.
return servers.filter(primaryFilter);
case 'primaryPreferred': {
const primary = servers.filter(primaryFilter);
// If there is a primary and it is not deprioritized, use the primary. Otherwise,
// check for secondaries.
const eligiblePrimary = primary.filter(isDeprioritizedFactory(deprioritized));
if (eligiblePrimary.length) {
return eligiblePrimary;
}
// If we make it here, we either have:
// 1. a deprioritized primary
// 2. no eligible primary
// secondaries take precedence of deprioritized primaries.
const secondaries = tagSetReducer(readPreference, maxStalenessReducer(readPreference, topologyDescription, servers.filter(secondaryFilter)));
const eligibleSecondaries = secondaries.filter(isDeprioritizedFactory(deprioritized));
if (eligibleSecondaries.length) {
return latencyWindowReducer(topologyDescription, eligibleSecondaries);
}
// if we make it here, we have no primaries or secondaries that not deprioritized.
// prefer the primary (which may not exist, if the topology has no primary).
// otherwise, return the secondaries (which also may not exist, but there is nothing else to check here).
return primary.length ? primary : latencyWindowReducer(topologyDescription, secondaries);
}
case 'nearest': {
const eligible = filterDeprioritized(tagSetReducer(readPreference, maxStalenessReducer(readPreference, topologyDescription, servers.filter(nearestFilter))), deprioritized);
return latencyWindowReducer(topologyDescription, eligible);
}
case 'secondary':
case 'secondaryPreferred': {
const secondaries = tagSetReducer(readPreference, maxStalenessReducer(readPreference, topologyDescription, servers.filter(secondaryFilter)));
const eligibleSecondaries = secondaries.filter(isDeprioritizedFactory(deprioritized));
if (eligibleSecondaries.length) {
return latencyWindowReducer(topologyDescription, eligibleSecondaries);
}
// we have no eligible secondaries, try for a primary if we can.
if (mode === read_preference_1.ReadPreference.SECONDARY_PREFERRED) {
const primary = servers.filter(primaryFilter);
// unlike readPreference=primary, here we do filter for deprioritized servers.
// if the primary is deprioritized, deprioritized secondaries take precedence.
const eligiblePrimary = primary.filter(isDeprioritizedFactory(deprioritized));
if (eligiblePrimary.length)
return eligiblePrimary;
// we have no eligible primary nor secondaries that have not been deprioritized
return secondaries.length
? latencyWindowReducer(topologyDescription, secondaries)
: primary;
}
// return all secondaries in the latency window.
return latencyWindowReducer(topologyDescription, secondaries);
}
default: {
const _exhaustiveCheck = mode;
throw new error_1.MongoRuntimeError(`unexpected readPreference=${mode} (should never happen). Please report a bug in the Node driver Jira project.`);
}
}
}
/**
* Returns a function which selects servers based on a provided read preference
*
* @param readPreference - The read preference to select with
*/
function readPreferenceServerSelector(readPreference) {
if (!readPreference.isValid()) {
throw new error_1.MongoInvalidArgumentError('Invalid read preference specified');
}
return function readPreferenceServers(topologyDescription, servers, deprioritized) {
switch (topologyDescription.type) {
case 'Single':
return latencyWindowReducer(topologyDescription, servers.filter(knownFilter));
case 'ReplicaSetNoPrimary':
case 'ReplicaSetWithPrimary':
return secondarySelector(readPreference, topologyDescription, servers, deprioritized);
case 'Sharded': {
const selectable = filterDeprioritized(servers, deprioritized);
return latencyWindowReducer(topologyDescription, selectable.filter(knownFilter));
}
case 'Unknown':
return [];
case 'LoadBalanced':
return servers.filter(loadBalancerFilter);
default: {
const _exhaustiveCheck = topologyDescription.type;
throw new error_1.MongoRuntimeError(`unexpected topology type: ${topologyDescription.type} (this should never happen). Please file a bug in the Node driver Jira project.`);
}
}
};
}
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