add a test program for evaluating depfile parse speed

configure.py

@@ -136,6 +136,7 @@ n.comment('Main executable is library plus main() function.')
 objs = cxx('ninja')
 n.build('ninja', 'link', objs, implicit=ninja_lib,
         variables=[('libs', '-L$builddir -lninja')])
+n.newline()
 
 n.comment('Tests all build into ninja_test executable.')
 objs = []
@@ -151,6 +152,12 @@ n.build('ninja_test', 'link', objs, implicit=ninja_lib,
                    ('ldflags', ' '.join(ldflags))])
 n.newline()
 
+n.comment('Perftest executable.')
+objs = cxx('parser_perftest')
+n.build('parser_perftest', 'link', objs, implicit=ninja_lib,
+        variables=[('libs', '-L$builddir -lninja')])
+n.newline()
+
 n.comment('Generate a graph using the "graph" tool.')
 n.rule('gendot',
        command='./ninja -t graph > $out')

src/parser_perftest.cc

@@ -0,0 +1,57 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// 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.
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "parsers.h"
+#include "util.h"
+
+int main(int argc, char* argv[]) {
+  if (argc < 2) {
+    printf("usage: %s <file1> <file2...>\n", argv[0]);
+    return 1;
+  }
+
+  for (int i = 1; i < argc; ++i) {
+    const char* filename = argv[i];
+
+    for (int limit = 1 << 10; limit < (1<<20); limit *= 2) {
+      int64_t start = GetTimeMillis();
+      for (int rep = 0; rep < limit; ++rep) {
+        string buf;
+        string err;
+        if (ReadFile(filename, &buf, &err) < 0) {
+          printf("%s: %s\n", filename, err.c_str());
+          return 1;
+        }
+
+        MakefileParser parser;
+        if (!parser.Parse(buf, &err)) {
+          printf("%s: %s\n", filename, err.c_str());
+          return 1;
+        }
+      }
+      int64_t end = GetTimeMillis();
+
+      if (end - start > 100) {
+        int delta = (int)(end - start);
+        printf("%s: %.2fus\n", filename, (float)(delta*1000 / (float)limit));
+        break;
+      }
+    }
+  }
+
+  return 0;
+}