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Object.defineProperty(exports, "__esModule", { value: true });
exports.readPreferenceServerSelector = exports.secondaryWritableServerSelector = exports.sameServerSelector = exports.writableServerSelector = exports.MIN_SECONDARY_WRITE_WIRE_VERSION = void 0;
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;
/**
* Returns a server selector that selects for writable servers
*/
function writableServerSelector() {
return function writableServer(topologyDescription, servers) {
return latencyWindowReducer(topologyDescription, servers.filter((s) => s.isWritable));
};
}
exports.writableServerSelector = writableServerSelector;
/**
* 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) {
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;
});
};
}
exports.sameServerSelector = sameServerSelector;
/**
* 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);
}
exports.secondaryWritableServerSelector = secondaryWritableServerSelector;
/**
* Reduces the passed in array of servers by the rules of the "Max Staleness" specification
* found here: https://github.com/mongodb/specifications/blob/master/source/max-staleness/max-staleness.rst
*
* @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.reduce((result, server) => {
const stalenessMS = server.lastUpdateTime -
server.lastWriteDate -
(primary.lastUpdateTime - primary.lastWriteDate) +
topologyDescription.heartbeatFrequencyMS;
const staleness = stalenessMS / 1000;
const maxStalenessSeconds = readPreference.maxStalenessSeconds ?? 0;
if (staleness <= maxStalenessSeconds) {
result.push(server);
}
return result;
}, []);
}
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.reduce((result, server) => {
const stalenessMS = sMax.lastWriteDate - server.lastWriteDate + topologyDescription.heartbeatFrequencyMS;
const staleness = stalenessMS / 1000;
const maxStalenessSeconds = readPreference.maxStalenessSeconds ?? 0;
if (staleness <= maxStalenessSeconds) {
result.push(server);
}
return result;
}, []);
}
return servers;
}
/**
* Determines whether a server's tags match a given set of tags
*
* @param tagSet - The requested tag set to match
* @param serverTags - The server's tags
*/
function tagSetMatch(tagSet, serverTags) {
const keys = Object.keys(tagSet);
const serverTagKeys = Object.keys(serverTags);
for (let i = 0; i < keys.length; ++i) {
const key = keys[i];
if (serverTagKeys.indexOf(key) === -1 || serverTags[key] !== tagSet[key]) {
return false;
}
}
return true;
}
/**
* 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(readPreference, servers) {
if (readPreference.tags == null ||
(Array.isArray(readPreference.tags) && readPreference.tags.length === 0)) {
return servers;
}
for (let i = 0; i < readPreference.tags.length; ++i) {
const tagSet = readPreference.tags[i];
const serversMatchingTagset = servers.reduce((matched, server) => {
if (tagSetMatch(tagSet, server.tags))
matched.push(server);
return matched;
}, []);
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:
* https://github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.rst
*
* @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.reduce((result, server) => {
if (server.roundTripTime <= high && server.roundTripTime >= low)
result.push(server);
return result;
}, []);
}
// 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;
}
/**
* 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 = []) {
const commonWireVersion = topologyDescription.commonWireVersion;
if (commonWireVersion &&
readPreference.minWireVersion &&
readPreference.minWireVersion > commonWireVersion) {
throw new error_1.MongoCompatibilityError(`Minimum wire version '${readPreference.minWireVersion}' required, but found '${commonWireVersion}'`);
}
if (topologyDescription.type === common_1.TopologyType.LoadBalanced) {
return servers.filter(loadBalancerFilter);
}
if (topologyDescription.type === common_1.TopologyType.Unknown) {
return [];
}
if (topologyDescription.type === common_1.TopologyType.Single) {
return latencyWindowReducer(topologyDescription, servers.filter(knownFilter));
}
if (topologyDescription.type === common_1.TopologyType.Sharded) {
const filtered = servers.filter(server => {
return !deprioritized.includes(server);
});
const selectable = filtered.length > 0 ? filtered : deprioritized;
return latencyWindowReducer(topologyDescription, selectable.filter(knownFilter));
}
const mode = readPreference.mode;
if (mode === read_preference_1.ReadPreference.PRIMARY) {
return servers.filter(primaryFilter);
}
if (mode === read_preference_1.ReadPreference.PRIMARY_PREFERRED) {
const result = servers.filter(primaryFilter);
if (result.length) {
return result;
}
}
const filter = mode === read_preference_1.ReadPreference.NEAREST ? nearestFilter : secondaryFilter;
const selectedServers = latencyWindowReducer(topologyDescription, tagSetReducer(readPreference, maxStalenessReducer(readPreference, topologyDescription, servers.filter(filter))));
if (mode === read_preference_1.ReadPreference.SECONDARY_PREFERRED && selectedServers.length === 0) {
return servers.filter(primaryFilter);
}
return selectedServers;
};
}
exports.readPreferenceServerSelector = readPreferenceServerSelector;
//# sourceMappingURL=server_selection.js.map |