Add file descriptor limit histogram to Simple Cache

We want to compare the open entry count to the file descriptor limit to see
if we're in danger of running the system out of fds.

BUG=

Review URL: https://chromiumcodereview.appspot.com/20117002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@215212 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 46 insertions, 0 deletions

diff --git a/net/disk_cache/simple/simple_backend_impl.cc b/net/disk_cache/simple/simple_backend_impl.cc
index c8a8e7c..1a0fef7 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -7,6 +7,10 @@
 #include <algorithm>
 #include <cstdlib>
 
+#if defined(OS_POSIX)
+#include <sys/resource.h>
+#endif
+
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/file_util.h"
@@ -14,6 +18,7 @@
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/single_thread_task_runner.h"
 #include "base/sys_info.h"
 #include "base/task_runner_util.h"
@@ -71,6 +76,46 @@ void MaybeCreateSequencedWorkerPool() {
   }
 }
 
+bool g_fd_limit_histogram_has_been_populated = false;
+
+void MaybeHistogramFdLimit() {
+  if (g_fd_limit_histogram_has_been_populated)
+    return;
+
+  // Used in histograms; add new entries at end.
+  enum FdLimitStatus {
+    FD_LIMIT_STATUS_UNSUPPORTED = 0,
+    FD_LIMIT_STATUS_FAILED      = 1,
+    FD_LIMIT_STATUS_SUCCEEDED   = 2,
+    FD_LIMIT_STATUS_MAX         = 3
+  };
+  FdLimitStatus fd_limit_status = FD_LIMIT_STATUS_UNSUPPORTED;
+  int soft_fd_limit = 0;
+  int hard_fd_limit = 0;
+
+#if defined(OS_POSIX)
+  struct rlimit nofile;
+  if (!getrlimit(RLIMIT_NOFILE, &nofile)) {
+    soft_fd_limit = nofile.rlim_cur;
+    hard_fd_limit = nofile.rlim_max;
+    fd_limit_status = FD_LIMIT_STATUS_SUCCEEDED;
+  } else {
+    fd_limit_status = FD_LIMIT_STATUS_FAILED;
+  }
+#endif
+
+  UMA_HISTOGRAM_ENUMERATION("SimpleCache.FileDescriptorLimitStatus",
+                            fd_limit_status, FD_LIMIT_STATUS_MAX);
+  if (fd_limit_status == FD_LIMIT_STATUS_SUCCEEDED) {
+    UMA_HISTOGRAM_SPARSE_SLOWLY("SimpleCache.FileDescriptorLimitSoft",
+                                soft_fd_limit);
+    UMA_HISTOGRAM_SPARSE_SLOWLY("SimpleCache.FileDescriptorLimitHard",
+                                hard_fd_limit);
+  }
+
+  g_fd_limit_histogram_has_been_populated = true;
+}
+
 // Must run on IO Thread.
 void DeleteBackendImpl(disk_cache::Backend** backend,
                        const net::CompletionCallback& callback,
@@ -177,6 +222,7 @@ SimpleBackendImpl::SimpleBackendImpl(const FilePath& path,
               SimpleEntryImpl::OPTIMISTIC_OPERATIONS :
               SimpleEntryImpl::NON_OPTIMISTIC_OPERATIONS),
       net_log_(net_log) {
+  MaybeHistogramFdLimit();
 }
 
 SimpleBackendImpl::~SimpleBackendImpl() {