align internal generator types with std::generator proposal

4 files changed, 56 insertions, 24 deletions

diff --git a/vespalib/src/tests/coro/generator/CMakeLists.txt b/vespalib/src/tests/coro/generator/CMakeLists.txt
index e2534274f7c..d2c8ec9b857 100644
--- a/vespalib/src/tests/coro/generator/CMakeLists.txt
+++ b/vespalib/src/tests/coro/generator/CMakeLists.txt
@@ -9,6 +9,7 @@ vespa_add_executable(vespalib_generator_test_app TEST
 vespa_add_executable(vespalib_generator_bench_app TEST
     SOURCES
     generator_bench.cpp
+    hidden_sequence.cpp
     DEPENDS
     vespalib
     GTest::GTest
diff --git a/vespalib/src/tests/coro/generator/generator_bench.cpp b/vespalib/src/tests/coro/generator/generator_bench.cpp
index ae0e0fce894..4fa9c6186f5 100644
--- a/vespalib/src/tests/coro/generator/generator_bench.cpp
+++ b/vespalib/src/tests/coro/generator/generator_bench.cpp
@@ -1,5 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
+#include "hidden_sequence.h"
 #include <vespa/vespalib/coro/generator.h>
 #include <vespa/vespalib/util/benchmark_timer.h>
 #include <vespa/vespalib/util/sequence.h>
@@ -11,23 +12,8 @@ using vespalib::coro::Generator;
 using vespalib::BenchmarkTimer;
 using vespalib::Sequence;
 
-size_t calc_sum(const std::vector<size_t> &values) {
-    size_t sum = 0;
-    for (auto&& value: values) {
-        sum += value;
-    }
-    return sum;
-}
-
-size_t calc_sum(Generator<size_t> values) {
-    size_t sum = 0;
-    for (auto&& value: values) {
-        sum += value;
-    }
-    return sum;
-}
-
-size_t calc_sum(Generator<const size_t &> values) {
+template <std::ranges::input_range T>
+size_t calc_sum(T &&values) {
     size_t sum = 0;
     for (auto&& value: values) {
         sum += value;
@@ -42,6 +28,7 @@ size_t calc_sum(Sequence<size_t> &seq) {
     }
     return sum;
 }
+size_t calc_sum(Sequence<size_t>::UP &ptr) { return calc_sum(*ptr); }
 
 std::vector<size_t> make_data() __attribute__((noinline));
 std::vector<size_t> make_data() {
@@ -83,9 +70,9 @@ size_t calc_sum_generator(const std::vector<size_t> &data) {
     return calc_sum(gen_values(data));
 }
 
-Generator<const size_t &> gen_values_noinline(const std::vector<size_t> &data) __attribute__((noinline));
-Generator<const size_t &> gen_values_noinline(const std::vector<size_t> &data) {
-    for (const size_t &value: data) {
+Generator<size_t> gen_values_noinline(const std::vector<size_t> &data) __attribute__((noinline));
+Generator<size_t> gen_values_noinline(const std::vector<size_t> &data) {
+    for (size_t value: data) {
         co_yield value;
     }
 }
@@ -104,22 +91,37 @@ double bench(auto fun, const std::vector<size_t> &data, size_t &res) {
     return timer.min_time() * 1000.0;
 }
 
+double bench_indirect(auto factory, const std::vector<size_t> &data, size_t &res) {
+    BenchmarkTimer timer(5.0);
+    while (timer.has_budget()) {
+        auto seq = factory(data);
+        timer.before();
+        res = calc_sum(seq);
+        timer.after();
+    }
+    return timer.min_time() * 1000.0;
+}
+
 TEST(GeneratorBench, direct_vs_generated_for_loop) {
     auto data = make_data();
-    size_t result[4] = { 0, 1, 2, 3 };
+    size_t result[5] = { 0, 1, 2, 3, 4 };
     double sequence_ms = bench(calc_sum_sequence, data, result[0]);
     fprintf(stderr, "sequence: %g ms\n", sequence_ms);
-    double generator_noinline_ms = bench(calc_sum_generator_noinline, data, result[1]);
+    double hidden_sequence_ms = bench_indirect(make_ext_seq, data, result[1]);
+    fprintf(stderr, "hidden sequence: %g ms\n", hidden_sequence_ms);
+    double generator_noinline_ms = bench(calc_sum_generator_noinline, data, result[2]);
     fprintf(stderr, "generator_noinline: %g ms\n", generator_noinline_ms);
-    double generator_ms = bench(calc_sum_generator, data, result[2]);
+    double generator_ms = bench(calc_sum_generator, data, result[3]);
     fprintf(stderr, "generator: %g ms\n", generator_ms);
-    double direct_ms = bench(calc_sum_direct, data, result[3]);
+    double direct_ms = bench(calc_sum_direct, data, result[4]);
     fprintf(stderr, "direct: %g ms\n", direct_ms);
     EXPECT_EQ(result[0], result[1]);
     EXPECT_EQ(result[0], result[2]);
     EXPECT_EQ(result[0], result[3]);
+    EXPECT_EQ(result[0], result[4]);
     fprintf(stderr, "ratio (generator/direct): %g\n", (generator_ms/direct_ms));
     fprintf(stderr, "ratio (generator_noinline/generator): %g\n", (generator_noinline_ms/generator_ms));
+    fprintf(stderr, "ratio (sequence/generator_noinline): %g\n", (sequence_ms/generator_noinline_ms));
     fprintf(stderr, "ratio (sequence/generator): %g\n", (sequence_ms/generator_ms));
 }
 
diff --git a/vespalib/src/tests/coro/generator/hidden_sequence.cpp b/vespalib/src/tests/coro/generator/hidden_sequence.cpp
new file mode 100644
index 00000000000..39eedb4623c
--- /dev/null
+++ b/vespalib/src/tests/coro/generator/hidden_sequence.cpp
@@ -0,0 +1,21 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "hidden_sequence.h"
+
+namespace {
+
+struct MyHiddenSeq : vespalib::Sequence<size_t> {
+    const std::vector<size_t> &data;
+    size_t pos;
+    MyHiddenSeq(const std::vector<size_t> &data_in)
+      : data(data_in), pos(0) {}
+    bool valid() const override { return pos < data.size(); }
+    size_t get() const override { return data[pos]; }
+    void next() override { ++pos; }
+};
+
+}
+
+vespalib::Sequence<size_t>::UP make_ext_seq(const std::vector<size_t> &data) {
+    return std::make_unique<MyHiddenSeq>(data);
+}
diff --git a/vespalib/src/tests/coro/generator/hidden_sequence.h b/vespalib/src/tests/coro/generator/hidden_sequence.h
new file mode 100644
index 00000000000..917b50b1129
--- /dev/null
+++ b/vespalib/src/tests/coro/generator/hidden_sequence.h
@@ -0,0 +1,8 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <vespa/vespalib/util/sequence.h>
+#include <vector>
+
+vespalib::Sequence<size_t>::UP make_ext_seq(const std::vector<size_t> &data);