3 files changed, 62 insertions, 70 deletions

diff --git a/src/mongo/db/commands/plan_cache_commands.cpp b/src/mongo/db/commands/plan_cache_commands.cpp
index da280a7c172..2728fc322e8 100644
--- a/src/mongo/db/commands/plan_cache_commands.cpp
+++ b/src/mongo/db/commands/plan_cache_commands.cpp
@@ -94,7 +94,6 @@ namespace {
         // the ActionType construction will be completed first.
         new PlanCacheListQueryShapes();
         new PlanCacheClear();
-        new PlanCacheDrop();
         new PlanCacheListPlans();
 
         return Status::OK();
@@ -244,7 +243,7 @@ namespace mongo {
     }
 
     PlanCacheClear::PlanCacheClear() : PlanCacheCommand("planCacheClear",
-        "Drops all cached queries in a collection.",
+        "Drops one or all cached queries in a collection.",
         ActionType::planCacheWrite) { }
 
     Status PlanCacheClear::runPlanCacheCommand(const string& ns, BSONObj& cmdObj,
@@ -257,53 +256,47 @@ namespace mongo {
         if (!status.isOK()) {
             return status;
         }
-        return clear(ns, planCache);
+        return clear(planCache, ns, cmdObj);
     }
 
     // static
-    Status PlanCacheClear::clear(const std::string& ns, PlanCache* planCache) {
+    Status PlanCacheClear::clear(PlanCache* planCache, const string& ns, const BSONObj& cmdObj) {
         invariant(planCache);
 
-        planCache->clear();
-
-        LOG(1) << ns << ": cleared plan cache";
+        // According to the specification, the planCacheClear command runs in two modes:
+        // - clear all query shapes; or
+        // - clear plans for single query shape when a query shape is described in the
+        //   command arguments.
+        if (cmdObj.hasField("query")) {
+            CanonicalQuery* cqRaw;
+            Status status = PlanCacheCommand::canonicalize(ns, cmdObj, &cqRaw);
+            if (!status.isOK()) {
+                return status;
+            }
 
-        return Status::OK();
-    }
+            scoped_ptr<CanonicalQuery> cq(cqRaw);
+            Status result = planCache->remove(*cq);
+            if (!result.isOK()) {
+                return result;
+            }
 
-    PlanCacheDrop::PlanCacheDrop() : PlanCacheCommand("planCacheDrop",
-        "Drops query shape from plan cache.",
-        ActionType::planCacheWrite) { }
+            LOG(1) << ns << ": removed plan cache entry - " << cq->getQueryObj().toString()
+                   << "(sort: " << cq->getParsed().getSort()
+                   << "; projection: " << cq->getParsed().getProj() << ")";
 
-    Status PlanCacheDrop::runPlanCacheCommand(const string& ns, BSONObj& cmdObj,
-                                              BSONObjBuilder* bob) {
-        Client::ReadContext readCtx(ns);
-        Client::Context& ctx = readCtx.ctx();
-        PlanCache* planCache;
-        Status status = getPlanCache(ctx.db(), ns, &planCache);
-        if (!status.isOK()) {
-            return status;
+            return Status::OK();
         }
-        return drop(planCache, ns, cmdObj);
-    }
 
-    // static
-    Status PlanCacheDrop::drop(PlanCache* planCache, const string& ns, const BSONObj& cmdObj) {
-        CanonicalQuery* cqRaw;
-        Status status = canonicalize(ns, cmdObj, &cqRaw);
-        if (!status.isOK()) {
-            return status;
+        // If query is not provided, make sure sort and projection are not in arguments.
+        // We do not want to clear the entire cache inadvertently when the user
+        // forgets to provide a value for "query".
+        if (cmdObj.hasField("sort") || cmdObj.hasField("projection")) {
+            return Status(ErrorCodes::BadValue, "sort or projection provided without query");
         }
 
-        scoped_ptr<CanonicalQuery> cq(cqRaw);
-        Status result = planCache->remove(*cq);
-        if (!result.isOK()) {
-            return result;
-        }
+        planCache->clear();
 
-        LOG(1) << ns << ": removed plan cache entry - " << cq->getQueryObj().toString()
-               << "(sort: " << cq->getParsed().getSort()
-               << "; projection: " << cq->getParsed().getProj() << ")";
+        LOG(1) << ns << ": cleared plan cache";
 
         return Status::OK();
     }
diff --git a/src/mongo/db/commands/plan_cache_commands.h b/src/mongo/db/commands/plan_cache_commands.h
index fd3c0832089..6cf666bce36 100644
--- a/src/mongo/db/commands/plan_cache_commands.h
+++ b/src/mongo/db/commands/plan_cache_commands.h
@@ -120,7 +120,12 @@ namespace mongo {
     /**
      * planCacheClear
      *
-     * { planCacheClear: <collection> }
+     * {
+     *     planCacheClear: <collection>,
+     *     query: <query>,
+     *     sort: <sort>,
+     *     projection: <projection>
+     * }
      *
      */
     class PlanCacheClear : public PlanCacheCommand {
@@ -130,32 +135,20 @@ namespace mongo {
 
         /**
          * Clears collection's plan cache.
+         * If query shape is provided, clears plans for that single query shape only.
          */
-        static Status clear(const std::string& ns, PlanCache* planCache);
-    };
-
-    /**
-     * planCacheDrop
-     *
-     * { planCacheDrop: <collection>, key: <key> } }
-     *
-     */
-    class PlanCacheDrop : public PlanCacheCommand {
-    public:
-        PlanCacheDrop();
-        virtual Status runPlanCacheCommand(const std::string& ns, BSONObj& cmdObj,
-                                           BSONObjBuilder* bob);
-
-        /**
-         * Drops using a cache key.
-         */
-        static Status drop(PlanCache* planCache,const std::string& ns,  const BSONObj& cmdObj);
+        static Status clear(PlanCache* planCache, const std::string& ns, const BSONObj& cmdObj);
     };
 
     /**
      * planCacheListPlans
      *
-     * { planCacheListPlans: <collection>, key: <key> } }
+     * {
+     *     planCacheListPlans: <collection>,
+     *     query: <query>,
+     *     sort: <sort>,
+     *     projection: <projection>
+     * }
      *
      */
     class PlanCacheListPlans : public PlanCacheCommand {
diff --git a/src/mongo/db/commands/plan_cache_commands_test.cpp b/src/mongo/db/commands/plan_cache_commands_test.cpp
index 66d8a3c9c29..0fdfad7da19 100644
--- a/src/mongo/db/commands/plan_cache_commands_test.cpp
+++ b/src/mongo/db/commands/plan_cache_commands_test.cpp
@@ -144,7 +144,7 @@ namespace {
      * Tests for planCacheClear
      */
 
-    TEST(PlanCacheCommandsTest, planCacheClearOneKey) {
+    TEST(PlanCacheCommandsTest, planCacheClearAllShapes) {
         // Create a canonical query
         CanonicalQuery* cqRaw;
         ASSERT_OK(CanonicalQuery::canonicalize(ns, fromjson("{a: 1}"), &cqRaw));
@@ -160,7 +160,7 @@ namespace {
         ASSERT_EQUALS(getShapes(planCache).size(), 1U);
 
         // Clear cache and confirm number of keys afterwards.
-        ASSERT_OK(PlanCacheClear::clear(ns, &planCache));
+        ASSERT_OK(PlanCacheClear::clear(&planCache, ns, BSONObj()));
         ASSERT_EQUALS(getShapes(planCache).size(), 0U);
     }
 
@@ -207,24 +207,30 @@ namespace {
     }
 
     /**
-     * Tests for planCacheDrop
+     * Tests for planCacheClear (single query shape)
      */
 
-    TEST(PlanCacheCommandsTest, planCacheDropInvalidParameter) {
+    TEST(PlanCacheCommandsTest, planCacheClearInvalidParameter) {
         PlanCache planCache;
-        // Missing query field is not ok.
-        ASSERT_NOT_OK(PlanCacheDrop::drop(&planCache, ns, BSONObj()));
-        // Query field type must be PlanCacheKey.
-        ASSERT_NOT_OK(PlanCacheDrop::drop(&planCache, ns, fromjson("{query: 12345}")));
-        ASSERT_NOT_OK(PlanCacheDrop::drop(&planCache, ns, fromjson("{query: /keyisnotregex/}")));
+        // Query field type must be BSON object.
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns, fromjson("{query: 12345}")));
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns, fromjson("{query: /keyisnotregex/}")));
+        // Query must pass canonicalization.
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns,
+                                            fromjson("{query: {a: {$no_such_op: 1}}}")));
+        // Sort present without query is an error.
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns, fromjson("{sort: {a: 1}}")));
+        // Projection present without query is an error.
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns,
+                                            fromjson("{projection: {_id: 0, a: 1}}")));
     }
 
-    TEST(PlanCacheCommandsTest, planCacheDropUnknownKey) {
+    TEST(PlanCacheCommandsTest, planCacheClearUnknownKey) {
         PlanCache planCache;
-        ASSERT_NOT_OK(PlanCacheDrop::drop(&planCache, ns, fromjson("{query: {a: 1}}")));
+        ASSERT_NOT_OK(PlanCacheClear::clear(&planCache, ns, fromjson("{query: {a: 1}}")));
     }
 
-    TEST(PlanCacheCommandsTest, planCacheDropOneKey) {
+    TEST(PlanCacheCommandsTest, planCacheClearOneKey) {
         // Create 2 canonical queries.
         CanonicalQuery* cqRaw;
         ASSERT_OK(CanonicalQuery::canonicalize(ns, fromjson("{a: 1}"), &cqRaw));
@@ -253,7 +259,7 @@ namespace {
 
         // Drop {b: 1} from cache. Make sure {a: 1} is still in cache afterwards.
         BSONObjBuilder bob;
-        ASSERT_OK(PlanCacheDrop::drop(&planCache, ns, BSON("query" << cqB->getQueryObj())));
+        ASSERT_OK(PlanCacheClear::clear(&planCache, ns, BSON("query" << cqB->getQueryObj())));
         vector<BSONObj> shapesAfter = getShapes(planCache);
         ASSERT_EQUALS(shapesAfter.size(), 1U);
         ASSERT_EQUALS(shapesAfter[0], shapeA);