QUIC - track the open and close states of disk cache entries of

net/http/disk_cache_based_quic_server_info.cc

Index: net/http/disk_cache_based_quic_server_info.cc
diff --git a/net/http/disk_cache_based_quic_server_info.cc b/net/http/disk_cache_based_quic_server_info.cc
index 13c53b7f2679bad8478ae2ccf4aebe0f38740244..51943cdf61767739b72ae04612f8ed0a7d1e7986 100644
--- a/net/http/disk_cache_based_quic_server_info.cc
+++ b/net/http/disk_cache_based_quic_server_info.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "net/base/completion_callback.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ -16,6 +17,18 @@
 
 namespace net {
 
+// Histogram for tracking down the state of disk_cache::Entry.
+enum DiskCacheEntryState {
+  DISK_CACHE_ENTRY_OPENED = 0,
+  DISK_CACHE_ENTRY_CLOSED = 1,
+  DISK_CACHE_ENTRY_NUM_STATES = 2,
+};
+
+void RecordDiskCacheEntryState(DiskCacheEntryState entry_state) {
+  UMA_HISTOGRAM_ENUMERATION("Net.QuicDiskCache.EntryState", entry_state,
+                            DISK_CACHE_ENTRY_NUM_STATES);
+}
+
 // Some APIs inside disk_cache take a handle that the caller must keep alive
 // until the API has finished its asynchronous execution.
 //
@@ -115,8 +128,10 @@ void DiskCacheBasedQuicServerInfo::Persist() {
 
 DiskCacheBasedQuicServerInfo::~DiskCacheBasedQuicServerInfo() {
   DCHECK(user_callback_.is_null());
-  if (entry_)
+  if (entry_) {
     entry_->Close();
+    RecordDiskCacheEntryState(DISK_CACHE_ENTRY_CLOSED);
+  }
 }
 
 std::string DiskCacheBasedQuicServerInfo::key() const {
@@ -197,6 +212,7 @@ int DiskCacheBasedQuicServerInfo::DoOpenComplete(int rv) {
     entry_ = data_shim_->entry;
     state_ = READ;
     found_entry_ = true;
+    RecordDiskCacheEntryState(DISK_CACHE_ENTRY_OPENED);
   } else {
     state_ = WAIT_FOR_DATA_READY_DONE;
   }
@@ -223,8 +239,11 @@ int DiskCacheBasedQuicServerInfo::DoCreateOrOpenComplete(int rv) {
   if (rv != OK) {
     state_ = SET_DONE;
   } else {
-    if (!entry_)
+    if (!entry_) {
       entry_ = data_shim_->entry;
+      RecordDiskCacheEntryState(DISK_CACHE_ENTRY_OPENED);
+    }
+    DCHECK(entry_);
     state_ = WRITE;
   }
   return OK;
@@ -284,16 +303,20 @@ int DiskCacheBasedQuicServerInfo::DoWaitForDataReadyDone() {
   ready_ = true;
   // We close the entry because, if we shutdown before ::Persist is called,
   // then we might leak a cache reference, which causes a DCHECK on shutdown.
-  if (entry_)
+  if (entry_) {
     entry_->Close();
+    RecordDiskCacheEntryState(DISK_CACHE_ENTRY_CLOSED);
+  }
   entry_ = NULL;
   Parse(data_);
   return OK;
 }
 
 int DiskCacheBasedQuicServerInfo::DoSetDone() {
-  if (entry_)
+  if (entry_) {
     entry_->Close();
+    RecordDiskCacheEntryState(DISK_CACHE_ENTRY_CLOSED);
+  }
   entry_ = NULL;
   new_data_.clear();
   state_ = NONE;