SERVER-33464 Initial Promise/Future implementation

1 files changed, 230 insertions, 0 deletions

diff --git a/src/mongo/util/future_bm.cpp b/src/mongo/util/future_bm.cpp
new file mode 100644
index 00000000000..28d57bfe010
--- /dev/null
+++ b/src/mongo/util/future_bm.cpp
@@ -0,0 +1,230 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include <benchmark/benchmark.h>
+
+#include "mongo/bson/inline_decls.h"
+#include "mongo/util/future.h"
+
+namespace mongo {
+
+NOINLINE_DECL int makeReadyInt() {
+    benchmark::ClobberMemory();
+    return 1;
+}
+
+void BM_plainIntReady(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(makeReadyInt() + 1);
+    }
+}
+
+NOINLINE_DECL Future<int> makeReadyFut() {
+    benchmark::ClobberMemory();
+    return Future<int>::makeReady(1);
+}
+
+void BM_futureIntReady(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(makeReadyFut().get() + 1);
+    }
+}
+
+void BM_futureIntReadyThen(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(makeReadyFut().then([](int i) { return i + 1; }).get());
+    }
+}
+
+NOINLINE_DECL Future<int> makeReadyFutWithPromise() {
+    benchmark::ClobberMemory();
+    Promise<int> p;
+    p.emplaceValue(1);  // before getFuture().
+    return p.getFuture();
+}
+
+void BM_futureIntReadyWithPromise(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(makeReadyFutWithPromise().get() + 1);
+    }
+}
+
+void BM_futureIntReadyWithPromiseThen(benchmark::State& state) {
+    for (auto _ : state) {
+        int i = makeReadyFutWithPromise().then([](int i) { return i + 1; }).get();
+        benchmark::DoNotOptimize(i);
+    }
+}
+
+NOINLINE_DECL Future<int> makeReadyFutWithPromise2() {
+    // This is the same as makeReadyFutWithPromise() except that this gets the Future first.
+    benchmark::ClobberMemory();
+    Promise<int> p;
+    auto fut = p.getFuture();
+    p.emplaceValue(1);  // after getFuture().
+    return fut;
+}
+
+void BM_futureIntReadyWithPromise2(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(makeReadyFutWithPromise().then([](int i) { return i + 1; }).get());
+    }
+}
+
+void BM_futureIntDeferredThen(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p;
+        auto fut = p.getFuture().then([](int i) { return i + 1; });
+        p.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+void BM_futureIntDeferredThenImmediate(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p;
+        auto fut = p.getFuture().then([](int i) { return Future<int>::makeReady(i + 1); });
+        p.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+
+void BM_futureIntDeferredThenReady(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        auto fut = p1.getFuture().then([&](int i) { return makeReadyFutWithPromise(); });
+        p1.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+void BM_futureIntDoubleDeferredThen(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        Promise<int> p2;
+        auto fut = p1.getFuture().then([&](int i) { return p2.getFuture(); });
+        p1.emplaceValue(1);
+        p2.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+void BM_futureInt3xDeferredThenNested(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        Promise<int> p2;
+        Promise<int> p3;
+        auto fut = p1.getFuture().then(
+            [&](int i) { return p2.getFuture().then([&](int) { return p3.getFuture(); }); });
+        p1.emplaceValue(1);
+        p2.emplaceValue(1);
+        p3.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+void BM_futureInt3xDeferredThenChained(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        Promise<int> p2;
+        Promise<int> p3;
+        auto fut = p1.getFuture().then([&](int i) { return p2.getFuture(); }).then([&](int i) {
+            return p3.getFuture();
+        });
+        p1.emplaceValue(1);
+        p2.emplaceValue(1);
+        p3.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+
+void BM_futureInt4xDeferredThenNested(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        Promise<int> p2;
+        Promise<int> p3;
+        Promise<int> p4;
+        auto fut = p1.getFuture().then([&](int i) {
+            return p2.getFuture().then(
+                [&](int) { return p3.getFuture().then([&](int) { return p4.getFuture(); }); });
+        });
+        p1.emplaceValue(1);
+        p2.emplaceValue(1);
+        p3.emplaceValue(1);
+        p4.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+void BM_futureInt4xDeferredThenChained(benchmark::State& state) {
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        Promise<int> p1;
+        Promise<int> p2;
+        Promise<int> p3;
+        Promise<int> p4;
+        auto fut = p1.getFuture()  //
+                       .then([&](int i) { return p2.getFuture(); })
+                       .then([&](int i) { return p3.getFuture(); })
+                       .then([&](int i) { return p4.getFuture(); });
+        p1.emplaceValue(1);
+        p2.emplaceValue(1);
+        p3.emplaceValue(1);
+        p4.emplaceValue(1);
+        benchmark::DoNotOptimize(std::move(fut).get());
+    }
+}
+
+
+BENCHMARK(BM_plainIntReady);
+BENCHMARK(BM_futureIntReady);
+BENCHMARK(BM_futureIntReadyThen);
+BENCHMARK(BM_futureIntReadyWithPromise);
+BENCHMARK(BM_futureIntReadyWithPromiseThen);
+BENCHMARK(BM_futureIntReadyWithPromise2);
+BENCHMARK(BM_futureIntDeferredThen);
+BENCHMARK(BM_futureIntDeferredThenImmediate);
+BENCHMARK(BM_futureIntDeferredThenReady);
+BENCHMARK(BM_futureIntDoubleDeferredThen);
+BENCHMARK(BM_futureInt3xDeferredThenNested);
+BENCHMARK(BM_futureInt3xDeferredThenChained);
+BENCHMARK(BM_futureInt4xDeferredThenNested);
+BENCHMARK(BM_futureInt4xDeferredThenChained);
+
+}  // namespace mongo