Add a simple microbenchmark framework, packaging, and sample tests.

src/platform/microbenchmark/benchmarks/readwrite.cc

Index: src/platform/microbenchmark/benchmarks/readwrite.cc
diff --git a/src/platform/microbenchmark/benchmarks/readwrite.cc b/src/platform/microbenchmark/benchmarks/readwrite.cc
new file mode 100644
index 0000000000000000000000000000000000000000..72614ee1eb7cbe49aee4eb9d840944be3c42fc3a
--- /dev/null
+++ b/src/platform/microbenchmark/benchmarks/readwrite.cc
@@ -0,0 +1,83 @@
+// Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+// Some portions Copyright (c) 2009 The Chromium Authors.
+//
+// Microbenchmark of basic read/write throughput
+#include "microbenchmark/microbenchmark.h"
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/unistd.h>
+#include <syscall.h>
+#include <time.h>
+
+namespace chromeos {
+namespace benchmarks {
+
+#define IO_SIZE 4096
+#define CALL_SYSCALL(_SCAF, syscallargs...) \
+  (_SCAF ? IO_SIZE : syscall(syscallargs))
+static long kDefaultAmount = 0x4000;
+static const char *kDevUrandom = "/dev/urandom";
+static const char *kDevNull = "/dev/null";
+
+// Lovely globals used from Setup->Test.
+static int rfd = -1;
+static int wfd = -1;
+static long amount = kDefaultAmount;
+
+static void ReadWriteSetup(uint64 runs) {
+  CommandLine *cl = CommandLine::ForCurrentProcess();
+  std::string amount_str = cl->GetSwitchValueASCII("readwrite-amount");
+  std::string source = cl->GetSwitchValueASCII("readwrite-source");
+  std::string destination = cl->GetSwitchValueASCII("readwrite-destination");
+
+  if (amount_str.empty()) {
+    LOG(INFO) << "--readwrite-amount is missing.";
+    LOG(INFO) << "Defaulting to " << amount << " bytes";
+  } else {
+    amount = strtol(amount_str.c_str(), NULL, 0);
+    if (amount < 0 || amount > 0xffffff) {
+      LOG(ERROR) << "Amount specified was too large: " << amount;
+      LOG(INFO) << "Using default amount of " << kDefaultAmount;
+    }
+    amount = kDefaultAmount;
+  }
+  if (source.empty()) {
+    LOG(INFO) << "--readwrite-source missing.";
+    LOG(INFO) << "Defaulting to /dev/urandom as a source";
+    source = kDevUrandom;
+  }
+  if (destination.empty()) {
+    LOG(INFO) << "--readwrite-destination missing.";
+    LOG(INFO) << "Defaulting to /dev/null as a destination";
+    destination = kDevNull;
+  }
+  wfd = open("/dev/null", O_WRONLY);
+  rfd = open("/dev/zero", O_RDONLY);
+  LOG_IF(FATAL, wfd < 0 || rfd < 0) << "Failed to open /dev/null or /dev/zero";
+}
+
+static void ReadWrite(bool scaffold_only) {
+  ssize_t so_far = 0;
+  ssize_t bytes = 0;
+  char buf[IO_SIZE];
+  while (so_far < amount) {
+    bytes = CALL_SYSCALL(scaffold_only, __NR_read, rfd, buf, sizeof(buf));
+    PLOG_IF(FATAL, bytes < 0) << "An unexpected error occurred during read.";
+    so_far += bytes;
+    PLOG_IF(FATAL,
+            CALL_SYSCALL(scaffold_only, __NR_write, wfd, buf, bytes) != bytes)
+           << "An unexpected error occurred during write.";
+  }
+}
+CHROMEOS_MICROBENCHMARK_WITH_SETUP(ReadWriteSetup, ReadWrite, 1000);
+#undef IO_SIZE
+#undef CALL_SYSCALL
+
+}  // namespace benchmarks
+}  // namespace chromeos