Add metrics for DHCP WPAD feature.

net/proxy/dhcp_proxy_script_fetcher_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/proxy/dhcp_proxy_script_fetcher_win.h"
 
+#include "base/metrics/histogram.h"
+#include "base/perftimer.h"
 #include "net/base/net_errors.h"
 #include "net/proxy/dhcp_proxy_script_adapter_fetcher_win.h"
 
 #include <winsock2.h>
 #include <iphlpapi.h>
 #pragma comment(lib, "iphlpapi.lib")
 
 namespace {
 
 // How long to wait at maximum after we get results (a PAC file or
 // knowledge that no PAC file is configured) from whichever network
 // adapter finishes first.
 const int kMaxWaitAfterFirstResultMs = 400;
 
+const int kGetAdaptersAddressesErrors[] = {
+  ERROR_ADDRESS_NOT_ASSOCIATED,
+  ERROR_BUFFER_OVERFLOW,
+  ERROR_INVALID_PARAMETER,
+  ERROR_NOT_ENOUGH_MEMORY,
+  ERROR_NO_DATA,
+};
+
 }  // namespace
 
 namespace net {
 
 DhcpProxyScriptFetcherWin::DhcpProxyScriptFetcherWin(
     URLRequestContext* url_request_context)
     : state_(STATE_START),
       ALLOW_THIS_IN_INITIALIZER_LIST(fetcher_callback_(
           this, &DhcpProxyScriptFetcherWin::OnFetcherDone)),
       num_pending_fetchers_(0),
       url_request_context_(url_request_context) {
   DCHECK(url_request_context_);
 }
 
 DhcpProxyScriptFetcherWin::~DhcpProxyScriptFetcherWin() {
-  Cancel();
+  // Count as user-initiated if we are not yet in STATE_DONE.
+  CancelImpl(true);
 }
 
 int DhcpProxyScriptFetcherWin::Fetch(string16* utf16_text,
                                      CompletionCallback* callback) {
   DCHECK(CalledOnValidThread());
   if (state_ != STATE_START && state_ != STATE_DONE) {
     NOTREACHED();
     return ERR_UNEXPECTED;
   }
 
+  fetch_start_time_ = base::TimeTicks::Now();
+
   std::set<std::string> adapter_names;
   if (!ImplGetCandidateAdapterNames(&adapter_names)) {
     return ERR_UNEXPECTED;
   }
   if (adapter_names.empty()) {
     return ERR_PAC_NOT_IN_DHCP;
   }
 
   state_ = STATE_NO_RESULTS;
 
   client_callback_ = callback;
   destination_string_ = utf16_text;
 
   for (std::set<std::string>::iterator it = adapter_names.begin();
        it != adapter_names.end();
        ++it) {
     DhcpProxyScriptAdapterFetcher* fetcher(ImplCreateAdapterFetcher());
     fetcher->Fetch(*it, &fetcher_callback_);
     fetchers_.push_back(fetcher);
   }
   num_pending_fetchers_ = fetchers_.size();
 
   return ERR_IO_PENDING;
 }
 
 void DhcpProxyScriptFetcherWin::Cancel() {
+  CancelImpl(true);
+}
+
+void DhcpProxyScriptFetcherWin::CancelImpl(bool user_initiated) {

[jar (doing other things), 2011/05/23 19:37:52]

Please switch to using an enumerated type, rather than a boolean here to
increase readability.  I found it very confusing to read CancelImpl(false), and
thought it was saying we don't really want to cancel :-/, and so I was forced to
read header files (or implementation) to be able to read the code.

[Jói, 2011/05/24 00:58:38]

I don't think an enumerated type would be warranted since this is not a public
interface.  However, I agree with the spirit of the comment, that as is, the
"CancelImpl" name gives you no clue as to what the boolean argument does.  I
have split this up now so that the Cancel() function does the UMA bit, and
CancelImpl takes no parameters.  Hope that clears it up.

   DCHECK(CalledOnValidThread());
 
   if (state_ != STATE_DONE) {
     wait_timer_.Stop();
     state_ = STATE_DONE;
 
     for (FetcherVector::iterator it = fetchers_.begin();
          it != fetchers_.end();
          ++it) {
       (*it)->Cancel();
     }
 
     fetchers_.reset();
+
+    if (user_initiated) {
+      // We only count this stat if the cancel was explicitly initiated by
+      // our client, and if we weren't already in STATE_DONE.
+      UMA_HISTOGRAM_TIMES("Net.DhcpWpadCancelTime",
+                          base::TimeTicks::Now() - fetch_start_time_);
+    }
   }
 }
 
 std::string DhcpProxyScriptFetcherWin::GetFetcherName() const {
   DCHECK(CalledOnValidThread());
   return "win";
 }
 
 const GURL& DhcpProxyScriptFetcherWin::GetPacURL() const {
   DCHECK(CalledOnValidThread());
@@ skipping 31 matching lines @@
   if (state_ == STATE_NO_RESULTS) {
     state_ = STATE_SOME_RESULTS;
     wait_timer_.Start(
         base::TimeDelta::FromMilliseconds(ImplGetMaxWaitMs()),
         this, &DhcpProxyScriptFetcherWin::OnWaitTimer);
   }
 }
 
 void DhcpProxyScriptFetcherWin::OnWaitTimer() {
   DCHECK_EQ(state_, STATE_SOME_RESULTS);
+
+  // These are intended to help us understand whether our timeout may
+  // be too aggressive or not aggressive enough.
+  UMA_HISTOGRAM_COUNTS_100("Net.DhcpWpadNumAdaptersAtWaitTimer",
+                           fetchers_.size());
+  UMA_HISTOGRAM_COUNTS_100("Net.DhcpWpadNumPendingAdaptersAtWaitTimer",
+                           num_pending_fetchers_);
+
   TransitionToDone();
 }
 
 void DhcpProxyScriptFetcherWin::TransitionToDone() {
   DCHECK(state_ == STATE_NO_RESULTS || state_ == STATE_SOME_RESULTS);
 
   // Should have returned immediately at Fetch() if no adapters to check.
   DCHECK(!fetchers_.empty());
 
   // Scan twice for the result; once through the whole list for success,
@@ skipping 18 matching lines @@
          ++it) {
       if ((*it)->DidFinish()) {
         result = (*it)->GetResult();
         if (result != ERR_PAC_NOT_IN_DHCP) {
           break;
         }
       }
     }
   }
 
-  Cancel();
+  CancelImpl(false);
   DCHECK_EQ(state_, STATE_DONE);
   DCHECK(fetchers_.empty());
 
+  UMA_HISTOGRAM_TIMES("Net.DhcpWpadCompletionTime",
+                      base::TimeTicks::Now() - fetch_start_time_);
+
+  if (result != OK) {
+    UMA_HISTOGRAM_CUSTOM_ENUMERATION(
+        "Net.DhcpWpadFetchError", std::abs(result), GetAllErrorCodesForUma());
+  }
+
   client_callback_->Run(result);
 }
 
 DhcpProxyScriptAdapterFetcher*
     DhcpProxyScriptFetcherWin::ImplCreateAdapterFetcher() {
   return new DhcpProxyScriptAdapterFetcher(url_request_context_);
 }
 
 bool DhcpProxyScriptFetcherWin::ImplGetCandidateAdapterNames(
     std::set<std::string>* adapter_names) {
   return GetCandidateAdapterNames(adapter_names);
 }
 
 int DhcpProxyScriptFetcherWin::ImplGetMaxWaitMs() {
   return kMaxWaitAfterFirstResultMs;
 }
 
 bool DhcpProxyScriptFetcherWin::GetCandidateAdapterNames(
     std::set<std::string>* adapter_names) {
   DCHECK(adapter_names);
   adapter_names->clear();
 
   // The GetAdaptersAddresses MSDN page recommends using a size of 15000 to
   // avoid reallocation.
   ULONG adapters_size = 15000;
   scoped_ptr_malloc<IP_ADAPTER_ADDRESSES> adapters;
   ULONG error = ERROR_SUCCESS;
   int num_tries = 0;
+
+  PerfTimer time_api_access;
   do {
     adapters.reset(
         reinterpret_cast<IP_ADAPTER_ADDRESSES*>(malloc(adapters_size)));
     // Return only unicast addresses, and skip information we do not need.
     error = GetAdaptersAddresses(AF_UNSPEC,
                                  GAA_FLAG_SKIP_ANYCAST |
                                  GAA_FLAG_SKIP_MULTICAST |
                                  GAA_FLAG_SKIP_DNS_SERVER |
                                  GAA_FLAG_SKIP_FRIENDLY_NAME,
                                  NULL,
                                  adapters.get(),
                                  &adapters_size);
     ++num_tries;
   } while (error == ERROR_BUFFER_OVERFLOW && num_tries <= 3);
 
+  // This is primarily to validate our belief that the GetAdaptersAddresses API
+  // function is fast enough to call synchronously from the network thread.
+  UMA_HISTOGRAM_TIMES("Net.DhcpWpadGetAdaptersAddressesTime",
+                      time_api_access.Elapsed());
+
+  if (error != ERROR_SUCCESS) {
+    UMA_HISTOGRAM_CUSTOM_ENUMERATION(
+        "Net.DhcpWpadGetAdaptersAddressesError",
+        error,
+        base::CustomHistogram::ArrayToCustomRanges(
+            kGetAdaptersAddressesErrors,
+            arraysize(kGetAdaptersAddressesErrors)));
+  }
+
   if (error == ERROR_NO_DATA) {
     // There are no adapters that we care about.
     return true;
   }
 
   if (error != ERROR_SUCCESS) {
     LOG(WARNING) << "Unexpected error retrieving WPAD configuration from DHCP.";
     return false;
   }
 
   IP_ADAPTER_ADDRESSES* adapter = NULL;
   for (adapter = adapters.get(); adapter; adapter = adapter->Next) {
     if (adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK)
       continue;
     if ((adapter->Flags & IP_ADAPTER_DHCP_ENABLED) == 0)
       continue;
 
     DCHECK(adapter->AdapterName);
     adapter_names->insert(adapter->AdapterName);
   }
 
   return true;
 }
 
 }  // namespace net