SERVER-16782 db.collection.stats() supports toggling of indexDetails and display of single index stats.

2 files changed, 139 insertions, 3 deletions

diff --git a/jstests/core/apitest_dbcollection.js b/jstests/core/apitest_dbcollection.js
index 22a837d2821..71af054beab 100644
--- a/jstests/core/apitest_dbcollection.js
+++ b/jstests/core/apitest_dbcollection.js
@@ -135,3 +135,90 @@ db.getCollection( "test_db" ).find();
 
 db.getCollection( "test_db" ).drop();
 assert(db.getCollection( "test_db" ).getIndexes().length == 0,24);  
+
+/*
+ * stats()
+ */
+
+ (function() {
+    var t = db.apttest_dbcollection;
+
+    // Non-existent collection.
+    t.drop();
+    assert.commandFailed(t.stats(),
+                         'db.collection.stats() should fail on non-existent collection');
+
+    // scale - passed to stats() as sole numerical argument or part of an options object.
+    t.drop();
+    assert.commandWorked(db.createCollection(t.getName(), {capped: true, size: 10*1024*1024}));
+    var collectionStats = assert.commandWorked(t.stats(1024*1024));
+    assert.eq(10, collectionStats.maxSize,
+              'db.collection.stats(scale) - capped collection size scaled incorrectly: ' +
+              tojson(collectionStats));
+    var collectionStats = assert.commandWorked(t.stats({scale: 1024*1024}));
+    assert.eq(10, collectionStats.maxSize,
+              'db.collection.stats({scale: N}) - capped collection size scaled incorrectly: ' +
+              tojson(collectionStats));
+
+    // indexDetails - If true, includes 'indexDetails' field in results. Default: false.
+    t.drop();
+    t.save({a: 1});
+    t.ensureIndex({a: 1});
+    collectionStats = assert.commandWorked(t.stats());
+    assert(!collectionStats.hasOwnProperty('indexDetails'),
+           'unexpected indexDetails found in db.collection.stats() result: ' +
+           tojson(collectionStats));
+    collectionStats = assert.commandWorked(t.stats({indexDetails: false}));
+    assert(!collectionStats.hasOwnProperty('indexDetails'),
+           'unexpected indexDetails found in db.collection.stats({indexDetails: true}) result: ' +
+           tojson(collectionStats));
+    collectionStats = assert.commandWorked(t.stats({indexDetails: true}));
+    assert(collectionStats.hasOwnProperty('indexDetails'),
+           'indexDetails missing from db.collection.stats({indexDetails: true}) result: ' +
+           tojson(collectionStats));
+
+    // Returns index name.
+    function getIndexName(indexKey) {
+        var indexes = t.getIndexes().filter(function(doc) {
+            return friendlyEqual(doc.key, indexKey);
+        });
+        assert.eq(1, indexes.length, tojson(indexKey) + ' not found in getIndexes() result: ' +
+                  tojson(t.getIndexes()));
+        return indexes[0].name;
+    }
+
+    function checkIndexDetails(options, indexName) {
+        var collectionStats = assert.commandWorked(t.stats(options));
+        assert(collectionStats.hasOwnProperty('indexDetails'),
+               'indexDetails missing from ' + 'db.collection.stats(' + tojson(options) +
+               ') result: ' + tojson(collectionStats));
+        // Currently, indexDetails is only supported with WiredTiger.
+        if (jsTest.options().storageEngine == undefined) { return; }
+        if (jsTest.options().storageEngine.toLowerCase() != "wiredtiger") { return; }
+        assert.eq(1, Object.keys(collectionStats.indexDetails).length,
+                  'indexDetails must have exactly one entry');
+        assert(collectionStats.indexDetails[indexName],
+               indexName + ' missing from indexDetails: ' + tojson(collectionStats.indexDetails));
+        assert.neq(0, Object.keys(collectionStats.indexDetails[indexName]).length,
+                   indexName + ' exists in indexDetails but contains no information: ' +
+                   tojson(collectionStats));
+    }
+
+    // indexDetailsKey - show indexDetails results for this index key only.
+    var indexKey = {a: 1};
+    var indexName = getIndexName(indexKey);
+    checkIndexDetails({indexDetails: true, indexDetailsKey: indexKey}, indexName);
+
+    // indexDetailsName - show indexDetails results for this index name only.
+    checkIndexDetails({indexDetails: true, indexDetailsName: indexName}, indexName);
+
+    // Cannot specify both indexDetailsKey and indexDetailsName.
+    var error = assert.throws(function() {
+        t.stats({indexDetails: true, indexDetailsKey: indexKey, indexDetailsName: indexName});
+    }, null, 'indexDetailsKey and indexDetailsName cannot be used at the same time');
+    assert.eq(Error, error.constructor,
+              'db.collection.stats() failed when both indexDetailsKey and indexDetailsName ' +
+              'are used but with incorrect error type');
+
+    t.drop();
+ }());
diff --git a/src/mongo/shell/collection.js b/src/mongo/shell/collection.js
index 4ce212201b7..c0033a3dbce 100644
--- a/src/mongo/shell/collection.js
+++ b/src/mongo/shell/collection.js
@@ -62,7 +62,8 @@ DBCollection.prototype.help = function () {
     print("\tdb." + shortName + ".renameCollection( newName , <dropTarget> ) renames the collection.");
     print("\tdb." + shortName + ".runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name");
     print("\tdb." + shortName + ".save(obj)");
-    print("\tdb." + shortName + ".stats()");
+    print("\tdb." + shortName + ".stats({scale: N, indexDetails: true/false, " +
+          "indexDetailsKey: <index key>, indexDetailsName: <index name>})");
     // print("\tdb." + shortName + ".diskStorageStats({[extent: <num>,] [granularity: <bytes>,] ...}) - analyze record layout on disk");
     // print("\tdb." + shortName + ".pagesInRAM({[extent: <num>,] [granularity: <bytes>,] ...}) - analyze resident memory pages");
     print("\tdb." + shortName + ".storageSize() - includes free space allocated to this collection");
@@ -1095,8 +1096,56 @@ DBCollection.prototype.getCollection = function( subName ){
     return this._db.getCollection( this._shortName + "." + subName );
 }
 
-DBCollection.prototype.stats = function( scale ){
-    return this._db.runCommand( { collstats : this._shortName , scale : scale } );
+/**
+  * scale: The scale at which to deliver results. Unless specified, this command returns all data
+  *        in bytes.
+  * indexDetails: Includes indexDetails field in results. Default: false.
+  * indexDetailsKey: If indexDetails is true, filter contents in indexDetails by this index key.
+  * indexDetailsname: If indexDetails is true, filter contents in indexDetails by this index name.
+  *
+  * It is an error to provide both indexDetailsKey and indexDetailsName.
+  */
+DBCollection.prototype.stats = function(args) {
+    'use strict';
+
+    // For backwards compatibility with db.collection.stats(scale).
+    var scale = isObject(args) ? args.scale : args;
+
+    var options = isObject(args) ? args : {};
+    if (options.indexDetailsKey && options.indexDetailsName) {
+        throw new Error('Cannot filter indexDetails on both indexDetailsKey and ' +
+                        'indexDetailsName');
+    }
+
+    var res = this._db.runCommand({collStats: this._shortName, scale: scale});
+    if (!res.ok) {
+        return res;
+    }
+
+    var newIndexDetails = {};
+    if (res.indexDetails) {
+        if (!options.indexDetails) {
+            delete res.indexDetails;
+        }
+        else if (isObject(options.indexDetailsKey)) {
+            this.getIndexes().forEach(function(spec) {
+                if (friendlyEqual(spec.key, options.indexDetailsKey) &&
+                    res.indexDetails[spec.name]) {
+                    newIndexDetails[spec.name] = res.indexDetails[spec.name];
+                }
+            });
+            res.indexDetails = newIndexDetails;
+        }
+        else if (options.indexDetailsName) {
+            if (res.indexDetails[options.indexDetailsName]) {
+                newIndexDetails[options.indexDetailsName] =
+                    res.indexDetails[options.indexDetailsName];
+            }
+            res.indexDetails = newIndexDetails;
+        }
+    }
+
+    return res;
 }
 
 DBCollection.prototype.dataSize = function(){