io:stream

db/sstable_test.cc

@@ -9,7 +9,7 @@
 namespace db {
 namespace {
 
-TEST(SSTableTest, basic) {
+TEST(SSTableTest, main) {
     io::MemoryFile file;
 
     // Build a SSTable.

io/BUILD

@@ -49,3 +49,23 @@ cc_library(
     hdrs = ["memory-file.h"],
     deps = [":file"],
 )
+
+cc_library(
+    name = "stream",
+    srcs = ["stream.cc"],
+    hdrs = ["stream.h"],
+    deps = [
+        ":file",
+        ":file-utils",
+    ],
+)
+
+cc_test(
+    name = "stream_test",
+    srcs = ["stream_test.cc"],
+    deps = [
+        ":stream",
+        ":memory-file",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

io/line-reader_test.cc

@@ -8,7 +8,7 @@
 namespace io {
 namespace {
 
-TEST(LineReaderTest, basic) {
+TEST(LineReaderTest, main) {
     MemoryFile file({'h', 'e', 'l', 'l', 'o', '\n',
                      'w', 'o', 'r', 'l', 'd', '\n'});
     LineReader reader(file, {});

io/posix/file_test.cc

@@ -9,7 +9,7 @@ namespace io {
 namespace posix {
 namespace {
 
-TEST(FileTest, basic) {
+TEST(FileTest, main) {
     std::string filename = absl::StrCat(getenv("TEST_TMPDIR"), "/test");
 
     // Create a file and use pwrite to overwrite a portion.

io/stream.cc

@@ -0,0 +1,36 @@
+#include "io/stream.h"
+
+#include "io/file-utils.h"
+
+namespace io {
+
+OStream::OStream(File &file)
+    : std::ostream(this),
+      file_(file) {
+    setp(buffer_.begin(), buffer_.end());
+}
+
+int OStream::sync() {
+    size_t size = pptr() - pbase();
+    if (!size) {
+        return 0;
+    }
+    if (io::write(file_, {pbase(), size})) {
+        return -1;
+    }
+    setp(buffer_.begin(), buffer_.end());
+    return 0;
+}
+
+int OStream::overflow(int c) {
+    if (sync() < 0) {
+        return EOF;
+    }
+    if (c != EOF) {
+        *pptr() = c;
+        pbump(1);
+    }
+    return 0;
+}
+
+}  // namespace io

io/stream.h

@@ -0,0 +1,27 @@
+#ifndef _IO_STREAM_H
+#define _IO_STREAM_H
+
+#include <array>
+#include <ostream>
+#include <streambuf>
+
+#include "io/file.h"
+
+namespace io {
+
+class OStream : private std::streambuf, public std::ostream {
+public:
+    explicit OStream(File &file);
+    ~OStream() override { sync(); }
+
+private:
+    int sync() override;
+    int overflow(int c) override;
+
+    File &file_;
+    std::array<char, 8192> buffer_;
+};
+
+}  // namespace io
+
+#endif  // _IO_STREAM_H

io/stream_test.cc

@@ -0,0 +1,21 @@
+#include "io/stream.h"
+
+#include "io/memory-file.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+namespace io {
+namespace {
+
+using ::testing::ElementsAre;
+
+TEST(OStreamTest, main) {
+    MemoryFile file;
+    OStream os(file);
+    os << "foobar" << std::flush;
+    EXPECT_THAT(file.content(), ElementsAre('f', 'o', 'o', 'b', 'a', 'r'));
+}
+
+}  // namespace
+}  // namespace io

util/BUILD

@@ -77,6 +77,8 @@ cc_binary(
     srcs = ["hash-filter_stats.cc"],
     deps = [
         ":hash-filter",
+        "//io:stream",
+        "//io/posix:file",
         "@com_google_absl//absl/random",
     ],
 )

util/hash-filter_stats.cc

@@ -1,11 +1,13 @@
 #include <cstdint>
-#include <iostream>
 #include <vector>
 
 #include "absl/random/random.h"
+#include "io/posix/file.h"
+#include "io/stream.h"
 #include "util/hash-filter.h"
 
 int main() {
+    io::OStream os(io::posix::stdout);
     absl::InsecureBitGen gen;
     util::HashFilter32 filter(262144);
     std::vector<uint64_t> fingerprints;
@@ -14,7 +16,7 @@ int main() {
         filter.insert(fingerprint);
         fingerprints.push_back(fingerprint);
     }
-    std::cout << "inserted " << filter.size() << std::endl;
+    os << "inserted " << filter.size() << std::endl;
 
     int true_positives = 0;
     int false_negatives = 0;
@@ -25,8 +27,8 @@ int main() {
             ++false_negatives;
         }
     }
-    std::cout << "true positives " << true_positives << std::endl;
-    std::cout << "false negatives " << false_negatives << std::endl;
+    os << "true positives " << true_positives << std::endl;
+    os << "false negatives " << false_negatives << std::endl;
 
     int false_positives = 0;
     int true_negatives = 0;
@@ -38,6 +40,6 @@ int main() {
             ++true_negatives;
         }
     }
-    std::cout << "false positives " << false_positives << std::endl;
-    std::cout << "true negatives " << true_negatives << std::endl;
+    os << "false positives " << false_positives << std::endl;
+    os << "true negatives " << true_negatives << std::endl;
 }