SERVER-19977 Re-work JS ObjectID

Rather than storing a string with the encoded oid, just store a pointer
to the oid and convert it to a string on demand for "str" access.

3 files changed, 67 insertions, 21 deletions

diff --git a/src/mongo/scripting/mozjs/oid.cpp b/src/mongo/scripting/mozjs/oid.cpp
index 8c0debaccc1..e24dd3f0aca 100644
--- a/src/mongo/scripting/mozjs/oid.cpp
+++ b/src/mongo/scripting/mozjs/oid.cpp
@@ -42,46 +42,86 @@ namespace mongo {
 namespace mozjs {
 
 const JSFunctionSpec OIDInfo::methods[2] = {
-    MONGO_ATTACH_JS_CONSTRAINED_METHOD(toString, OIDInfo), JS_FS_END,
+    MONGO_ATTACH_JS_CONSTRAINED_METHOD_NO_PROTO(toString, OIDInfo), JS_FS_END,
 };
 
 const char* const OIDInfo::className = "ObjectId";
 
-void OIDInfo::Functions::toString::call(JSContext* cx, JS::CallArgs args) {
-    ObjectWrapper o(cx, args.thisv());
+void OIDInfo::finalize(JSFreeOp* fop, JSObject* obj) {
+    auto oid = static_cast<OID*>(JS_GetPrivate(obj));
 
-    if (!o.hasField("str"))
-        uasserted(ErrorCodes::BadValue, "Must have \"str\" field");
+    if (oid) {
+        delete oid;
+    }
+}
 
-    JS::RootedValue value(cx);
-    o.getValue("str", &value);
+void OIDInfo::Functions::toString::call(JSContext* cx, JS::CallArgs args) {
+    auto oid = static_cast<OID*>(JS_GetPrivate(args.thisv().toObjectOrNull()));
 
-    std::string str = str::stream() << "ObjectId(\"" << ValueWriter(cx, value).toString() << "\")";
+    std::string str = str::stream() << "ObjectId(\"" << oid->toString() << "\")";
 
     ValueReader(cx, args.rval()).fromStringData(str);
 }
 
-void OIDInfo::construct(JSContext* cx, JS::CallArgs args) {
-    auto scope = getScope(cx);
+void OIDInfo::Functions::getter::call(JSContext* cx, JS::CallArgs args) {
+    auto oid = static_cast<OID*>(JS_GetPrivate(args.thisv().toObjectOrNull()));
 
-    auto oid = stdx::make_unique<OID>();
+    ValueReader(cx, args.rval()).fromStringData(oid->toString());
+}
 
+void OIDInfo::construct(JSContext* cx, JS::CallArgs args) {
+    OID oid;
     if (args.length() == 0) {
-        oid->init();
+        oid.init();
     } else {
         auto str = ValueWriter(cx, args.get(0)).toString();
 
         Scope::validateObjectIdString(str);
-        oid->init(str);
+        oid.init(str);
     }
 
+    make(cx, oid, args.rval());
+}
+
+void OIDInfo::make(JSContext* cx, const OID& oid, JS::MutableHandleValue out) {
+    auto scope = getScope(cx);
+
+    auto oidHolder = stdx::make_unique<OID>(oid);
     JS::RootedObject thisv(cx);
     scope->getProto<OIDInfo>().newObject(&thisv);
-    ObjectWrapper o(cx, thisv);
+    JS_SetPrivate(thisv, oidHolder.release());
+
+    out.setObjectOrNull(thisv);
+}
+
+OID OIDInfo::getOID(JSContext* cx, JS::HandleValue value) {
+    JS::RootedObject obj(cx, value.toObjectOrNull());
+    return getOID(cx, obj);
+}
 
-    o.setString("str", oid->toString());
+OID OIDInfo::getOID(JSContext* cx, JS::HandleObject object) {
+    auto oid = static_cast<OID*>(JS_GetPrivate(object));
 
-    args.rval().setObjectOrNull(thisv);
+    if (oid) {
+        return *oid;
+    }
+
+    uasserted(ErrorCodes::BadValue, "Can't call getOID on OID prototype");
+}
+
+void OIDInfo::postInstall(JSContext* cx, JS::HandleObject global, JS::HandleObject proto) {
+    JS::RootedValue undef(cx);
+    undef.setUndefined();
+
+    if (!JS_DefinePropertyById(cx,
+                               proto,
+                               getScope(cx)->getInternedStringId(InternedString::str),
+                               undef,
+                               JSPROP_READONLY | JSPROP_ENUMERATE | JSPROP_SHARED,
+                               smUtils::wrapConstrainedMethod<Functions::getter, true, OIDInfo>,
+                               nullptr)) {
+        uasserted(ErrorCodes::JSInterpreterFailure, "Failed to JS_DefinePropertyById");
+    }
 }
 
 }  // namespace mozjs
diff --git a/src/mongo/scripting/mozjs/oid.h b/src/mongo/scripting/mozjs/oid.h
index 8171d2d2aac..3d723b97003 100644
--- a/src/mongo/scripting/mozjs/oid.h
+++ b/src/mongo/scripting/mozjs/oid.h
@@ -40,14 +40,24 @@ namespace mozjs {
  */
 struct OIDInfo : public BaseInfo {
     static void construct(JSContext* cx, JS::CallArgs args);
+    static void finalize(JSFreeOp* fop, JSObject* obj);
 
     struct Functions {
+        MONGO_DECLARE_JS_FUNCTION(getter);
         MONGO_DECLARE_JS_FUNCTION(toString);
     };
 
     static const JSFunctionSpec methods[2];
 
+    static const unsigned classFlags = JSCLASS_HAS_PRIVATE;
+
     static const char* const className;
+
+    static void postInstall(JSContext* cx, JS::HandleObject global, JS::HandleObject proto);
+
+    static void make(JSContext* cx, const OID& oid, JS::MutableHandleValue out);
+    static OID getOID(JSContext* cx, JS::HandleValue value);
+    static OID getOID(JSContext* cx, JS::HandleObject object);
 };
 
 }  // namespace mozjs
diff --git a/src/mongo/scripting/mozjs/valuereader.cpp b/src/mongo/scripting/mozjs/valuereader.cpp
index 71be53c6ff2..b78ed461297 100644
--- a/src/mongo/scripting/mozjs/valuereader.cpp
+++ b/src/mongo/scripting/mozjs/valuereader.cpp
@@ -66,11 +66,7 @@ void ValueReader::fromBSONElement(const BSONElement& elem, const BSONObj& parent
             fromStringData(elem.valueStringData());
             return;
         case mongo::jstOID: {
-            JS::AutoValueArray<1> args(_context);
-
-            ValueReader(_context, args[0]).fromStringData(elem.OID().toString());
-
-            scope->getProto<OIDInfo>().newInstance(args, _value);
+            OIDInfo::make(_context, elem.OID(), _value);
             return;
         }
         case mongo::NumberDouble: