Introduce multi-threaded/multi-version client support for GRV caching

bindings/c/CMakeLists.txt

@@ -1,6 +1,8 @@
 set(FDB_C_SRCS
   fdb_c.cpp
-  foundationdb/fdb_c.h)
+  foundationdb/fdb_c.h
+  foundationdb/fdb_c_internal.h
+  foundationdb/fdb_c_types.h)
 
 file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/foundationdb)
 

bindings/c/fdb_c.cpp

@@ -19,13 +19,15 @@
  */
 
 #include "fdbclient/FDBTypes.h"
+#include "flow/ProtocolVersion.h"
 #include <cstdint>
 #define FDB_API_VERSION 710
 #define FDB_INCLUDE_LEGACY_TYPES
 
 #include "fdbclient/MultiVersionTransaction.h"
 #include "fdbclient/MultiVersionAssignmentVars.h"
 #include "foundationdb/fdb_c.h"
+#include "foundationdb/fdb_c_internal.h"
 
 int g_api_version = 0;
 
@@ -293,6 +295,10 @@ extern "C" DLLEXPORT fdb_error_t fdb_future_get_mappedkeyvalue_array(FDBFuture*
 	                 *out_more = rrr.more;);
 }
 
+extern "C" DLLEXPORT fdb_error_t fdb_future_get_shared_state(FDBFuture* f, DatabaseSharedState** outPtr) {
+	CATCH_AND_RETURN(*outPtr = (DatabaseSharedState*)((TSAV(DatabaseSharedState*, f)->get())););
+}
+
 extern "C" DLLEXPORT fdb_error_t fdb_future_get_string_array(FDBFuture* f, const char*** out_strings, int* out_count) {
 	CATCH_AND_RETURN(Standalone<VectorRef<const char*>> na = TSAV(Standalone<VectorRef<const char*>>, f)->get();
 	                 *out_strings = (const char**)na.begin();
@@ -426,6 +432,17 @@ extern "C" DLLEXPORT FDBFuture* fdb_database_create_snapshot(FDBDatabase* db,
 	                        .extractPtr());
 }
 
+extern "C" DLLEXPORT FDBFuture* fdb_database_create_shared_state(FDBDatabase* db) {
+	return (FDBFuture*)(DB(db)->createSharedState().extractPtr());
+}
+
+extern "C" DLLEXPORT void fdb_database_set_shared_state(FDBDatabase* db, DatabaseSharedState* p) {
+	try {
+		DB(db)->setSharedState(p);
+	} catch (...) {
+	}
+}
+
 // Get network thread busyness (updated every 1s)
 // A value of 0 indicates that the client is more or less idle
 // A value of 1 (or more) indicates that the client is saturated

bindings/c/foundationdb/fdb_c.h

@@ -58,21 +58,12 @@
 #include <stdint.h>
 
 #include "fdb_c_options.g.h"
+#include "fdb_c_types.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/* Pointers to these opaque types represent objects in the FDB API */
-typedef struct FDB_future FDBFuture;
-typedef struct FDB_result FDBResult;
-typedef struct FDB_database FDBDatabase;
-typedef struct FDB_tenant FDBTenant;
-typedef struct FDB_transaction FDBTransaction;
-
-typedef int fdb_error_t;
-typedef int fdb_bool_t;
-
 DLLEXPORT const char* fdb_get_error(fdb_error_t code);
 
 DLLEXPORT fdb_bool_t fdb_error_predicate(int predicate_test, fdb_error_t code);

bindings/c/foundationdb/fdb_c_internal.h

@@ -0,0 +1,52 @@
+/*
+ * fdb_c_internal.h
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FDB_C_INTERNAL_H
+#define FDB_C_INTERNAL_H
+#include "flow/ProtocolVersion.h"
+#pragma once
+
+#ifndef DLLEXPORT
+#define DLLEXPORT
+#endif
+
+#ifndef WARN_UNUSED_RESULT
+#define WARN_UNUSED_RESULT
+#endif
+
+#include "fdb_c_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// forward declaration and typedef
+typedef struct DatabaseSharedState DatabaseSharedState;
+
+DLLEXPORT FDBFuture* fdb_database_create_shared_state(FDBDatabase* db);
+
+DLLEXPORT void fdb_database_set_shared_state(FDBDatabase* db, DatabaseSharedState* p);
+
+DLLEXPORT WARN_UNUSED_RESULT fdb_error_t fdb_future_get_shared_state(FDBFuture* f, DatabaseSharedState** outPtr);
+
+#ifdef __cplusplus
+}
+#endif
+#endif

bindings/c/foundationdb/fdb_c_types.h

@@ -0,0 +1,47 @@
+/*
+ * fdb_c_types.h
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FDB_C_TYPES_H
+#define FDB_C_TYPES_H
+#pragma once
+
+#ifndef DLLEXPORT
+#define DLLEXPORT
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Pointers to these opaque types represent objects in the FDB API */
+typedef struct FDB_future FDBFuture;
+typedef struct FDB_result FDBResult;
+typedef struct FDB_cluster FDBCluster;
+typedef struct FDB_database FDBDatabase;
+typedef struct FDB_tenant FDBTenant;
+typedef struct FDB_transaction FDBTransaction;
+
+typedef int fdb_error_t;
+typedef int fdb_bool_t;
+
+#ifdef __cplusplus
+}
+#endif
+#endif

bindings/c/test/apitester/TesterCorrectnessWorkload.cpp

@@ -83,8 +83,7 @@ class ApiCorrectnessWorkload : public ApiWorkload {
 			    auto results = std::make_shared<std::vector<std::optional<std::string>>>();
 			    execTransaction(
 			        [kvPairs, results](auto ctx) {
-				        // TODO: Enable after merging with GRV caching
-				        // ctx->tx()->setOption(FDB_TR_OPTION_USE_GRV_CACHE);
+				        ctx->tx()->setOption(FDB_TR_OPTION_USE_GRV_CACHE);
 				        auto futures = std::make_shared<std::vector<Future>>();
 				        for (const auto& kv : *kvPairs) {
 					        futures->push_back(ctx->tx()->get(kv.key, false));

fdbclient/DatabaseContext.h

@@ -29,6 +29,7 @@
 #include <unordered_map>
 #pragma once
 
+#include "fdbclient/FDBTypes.h"
 #include "fdbclient/NativeAPI.actor.h"
 #include "fdbclient/KeyRangeMap.h"
 #include "fdbclient/CommitProxyInterface.h"
@@ -519,6 +520,11 @@ class DatabaseContext : public ReferenceCounted<DatabaseContext>, public FastAll
 	int outstandingWatches;
 	int maxOutstandingWatches;
 
+	// Manage any shared state that may be used by MVC
+	DatabaseSharedState* sharedStatePtr;
+	Future<DatabaseSharedState*> initSharedState();
+	void setSharedState(DatabaseSharedState* p);
+
 	// GRV Cache
 	// Database-level read version cache storing the most recent successful GRV as well as the time it was requested.
 	double lastGrvTime;

fdbclient/FDBTypes.h

@@ -28,6 +28,8 @@
 #include <unordered_set>
 
 #include "flow/Arena.h"
+#include "flow/FastRef.h"
+#include "flow/ProtocolVersion.h"
 #include "flow/flow.h"
 
 enum class TraceFlags : uint8_t { unsampled = 0b00000000, sampled = 0b00000001 };
@@ -1350,6 +1352,29 @@ struct TenantMode {
 
 	uint32_t mode;
 };
+struct GRVCacheSpace {
+	Version cachedReadVersion;
+	double lastGrvTime;
+
+	GRVCacheSpace() : cachedReadVersion(Version(0)), lastGrvTime(0.0) {}
+};
+
+// This structure can be extended in the future to include additional features that required a shared state
+struct DatabaseSharedState {
+	// These two members should always be listed first, in this order.
+	// This is to preserve compatibility with future updates of this shared state
+	// and ensures the MVC does not attempt to access methods incorrectly
+	// due to newly introduced offsets in the structure.
+	const ProtocolVersion protocolVersion;
+	void (*delRef)(DatabaseSharedState*);
+
+	Mutex mutexLock;
+	GRVCacheSpace grvCacheSpace;
+	std::atomic<int> refCount;
+
+	DatabaseSharedState()
+	  : protocolVersion(currentProtocolVersion), mutexLock(Mutex()), grvCacheSpace(GRVCacheSpace()), refCount(0) {}
+};
 
 inline bool isValidPerpetualStorageWiggleLocality(std::string locality) {
 	int pos = locality.find(':');

fdbclient/IClientApi.h

@@ -20,6 +20,7 @@
 
 #ifndef FDBCLIENT_ICLIENTAPI_H
 #define FDBCLIENT_ICLIENTAPI_H
+#include "flow/ProtocolVersion.h"
 #pragma once
 
 #include "fdbclient/FDBOptions.g.h"
@@ -151,6 +152,10 @@ class IDatabase {
 	// Management API, create snapshot
 	virtual ThreadFuture<Void> createSnapshot(const StringRef& uid, const StringRef& snapshot_command) = 0;
 
+	// Interface to manage shared state across multiple connections to the same Database
+	virtual ThreadFuture<DatabaseSharedState*> createSharedState() = 0;
+	virtual void setSharedState(DatabaseSharedState* p) = 0;
+
 	// used in template functions as the Transaction type that can be created through createTransaction()
 	using TransactionT = ITransaction;
 };