Plasma manager performance: speed up wait with a wait request object map (#427)

* plasma manager perf: speedup wait with a wait request object map

* removing duplicate == operator in plasma store

* fix serialization test

* code cleanup

* minor cleanup

* factoring out uniqueid hash and equality operators into common

* plasma manager: c++ify the WaitRequest struct

* plasma manager: get rid of the initial object request malloc

* cleanup

* linting

* cleanups and fix compiler warnings

* compiler warnings and linting

src/common/common.cc

@@ -7,6 +7,7 @@
 #include <fcntl.h>
 
 #include "io.h"
+#include <functional>
 
 /* This is used to define the array of object IDs. */
 const UT_icd object_id_icd = {sizeof(ObjectID), NULL, NULL, NULL};
@@ -29,6 +30,11 @@ UniqueID globally_unique_id(void) {
   return result;
 }
 
+/* ObjectID equality function. */
+bool operator==(const ObjectID &x, const ObjectID &y) {
+  return UNIQUE_ID_EQ(x, y);
+}
+
 bool ObjectID_equal(ObjectID first_id, ObjectID second_id) {
   return UNIQUE_ID_EQ(first_id, second_id);
 }

src/common/common.h

@@ -13,6 +13,7 @@
 
 #include "utarray.h"
 #ifdef __cplusplus
+#include <functional>
 extern "C" {
 #endif
 #include "sha256.h"
@@ -152,6 +153,20 @@ UniqueID globally_unique_id(void);
 
 typedef UniqueID ObjectID;
 
+#ifdef __cplusplus
+
+struct UniqueIDHasher {
+  /* ObjectID hashing function. */
+  size_t operator()(const UniqueID &id) const {
+    size_t result;
+    memcpy(&result, id.id + UNIQUE_ID_SIZE - sizeof(size_t), sizeof(size_t));
+    return result;
+  }
+};
+
+bool operator==(const ObjectID &x, const ObjectID &y);
+#endif
+
 #define ID_STRING_SIZE (2 * UNIQUE_ID_SIZE + 1)
 
 /**