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/**
* Use prototype overrides to set read preference to "secondary" when running tests.
*/
(function() {
"use strict";
load("jstests/libs/override_methods/override_helpers.js");
const kReadPreferenceSecondary = {mode: "secondary"};
const kCommandsSupportingReadPreference = new Set([
"aggregate",
"collStats",
"count",
"dbStats",
"distinct",
"find",
"geoNear",
"geoSearch",
"group",
"mapReduce",
"mapreduce",
"parallelCollectionScan",
]);
function runCommandWithReadPreferenceSecondary(
conn, dbName, commandName, commandObj, func, makeFuncArgs) {
if (typeof commandObj !== "object" || commandObj === null) {
return func.apply(conn, makeFuncArgs(commandObj));
}
// If the command is in a wrapped form, then we look for the actual command object inside
// the query/$query object.
let commandObjUnwrapped = commandObj;
if (commandName === "query" || commandName === "$query") {
commandObjUnwrapped = commandObj[commandName];
commandName = Object.keys(commandObjUnwrapped)[0];
}
let shouldForceReadPreference = kCommandsSupportingReadPreference.has(commandName);
if (OverrideHelpers.isAggregationWithOutStage(commandName, commandObjUnwrapped)) {
// An aggregation with a $out stage must be sent to the primary.
shouldForceReadPreference = false;
} else if ((commandName === "mapReduce" || commandName === "mapreduce") &&
!OverrideHelpers.isMapReduceWithInlineOutput(commandName, commandObjUnwrapped)) {
// A map-reduce operation with non-inline output must be sent to the primary.
shouldForceReadPreference = false;
}
if (shouldForceReadPreference) {
if (commandObj === commandObjUnwrapped) {
// We wrap the command object using a "query" field rather than a "$query" field to
// match the implementation of DB.prototype._attachReadPreferenceToCommand().
commandObj = {query: commandObj};
} else {
// We create a copy of 'commandObj' to avoid mutating the parameter the caller
// specified.
commandObj = Object.assign({}, commandObj);
}
if (commandObj.hasOwnProperty("$readPreference") &&
!bsonBinaryEqual({_: commandObj.$readPreference}, {_: kReadPreferenceSecondary})) {
throw new Error("Cowardly refusing to override read preference of command: " +
tojson(commandObj));
}
commandObj.$readPreference = kReadPreferenceSecondary;
}
return func.apply(conn, makeFuncArgs(commandObj));
}
OverrideHelpers.prependOverrideInParallelShell(
"jstests/libs/override_methods/set_read_preference_secondary.js");
OverrideHelpers.overrideRunCommand(runCommandWithReadPreferenceSecondary);
})();
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