Remove unused code from MetricsService

Per discussion, this code is essentially all unused (the server never sends the node this looks for at the top level), and we don't expect to need it at this point, so take it out. If we do need some of this capability, we can add pieces back as necessary--with tests!

BUG=None
TEST=Existing MetricsServer tests, but mostly watching for unexpected changes in dashboards.

Review URL: http://codereview.chromium.org/6862001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@81745 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 7 insertions, 222 deletions

diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index bac7155..cfe83f2 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -228,8 +228,8 @@ static const int kInitialInterlogDuration = 60;  // one minute
 // data.
 static const int kMaxHistogramGatheringWaitDuration = 60000;  // 60 seconds.
 
-// The default maximum number of events in a log uploaded to the UMA server.
-static const int kInitialEventLimit = 2400;
+// The maximum number of events in a log uploaded to the UMA server.
+static const int kEventLimit = 2400;
 
 // If an upload fails, and the transmission was over this byte count, then we
 // will discard the log, and not try to retransmit it.  We also don't persist
@@ -445,7 +445,6 @@ MetricsService::MetricsService()
       ALLOW_THIS_IN_INITIALIZER_LIST(log_sender_factory_(this)),
       ALLOW_THIS_IN_INITIALIZER_LIST(state_saver_factory_(this)),
       interlog_duration_(TimeDelta::FromSeconds(kInitialInterlogDuration)),
-      log_event_limit_(kInitialEventLimit),
       timer_pending_(false) {
   DCHECK(IsSingleThreaded());
   InitializeMetricsState();
@@ -852,7 +851,7 @@ void MetricsService::StopRecording(MetricsLogBase** log) {
 
   // TODO(jar): Integrate bounds on log recording more consistently, so that we
   // can stop recording logs that are too big much sooner.
-  if (current_log_->num_events() > log_event_limit_) {
+  if (current_log_->num_events() > kEventLimit) {
     UMA_HISTOGRAM_COUNTS("UMA.Discarded Log Events",
                          current_log_->num_events());
     current_log_->CloseLog();
@@ -1398,16 +1397,13 @@ void MetricsService::OnURLFetchComplete(const URLFetcher* source,
     if (local_state)
       local_state->ScheduleSavePersistentPrefs();
 
-    // Provide a default (free of exponetial backoff, other varances) in case
-    // the server does not specify a value.
-    interlog_duration_ = TimeDelta::FromSeconds(kMinSecondsPerLog);
-
-    GetSettingsFromResponseData(data);
-    // Override server specified interlog delay if there are unsent logs to
-    // transmit.
+    // Override usual interlog delay if there are unsent logs to transmit,
+    // otherwise reset back to default.
     if (unsent_logs()) {
       DCHECK(state_ < SENDING_CURRENT_LOGS);
       interlog_duration_ = TimeDelta::FromSeconds(kUnsentLogDelay);
+    } else {
+      interlog_duration_ = TimeDelta::FromSeconds(kMinSecondsPerLog);
     }
   }
 
@@ -1437,167 +1433,6 @@ void MetricsService::HandleBadResponseCode() {
   }
 }
 
-void MetricsService::GetSettingsFromResponseData(const std::string& data) {
-  // We assume that the file is structured as a block opened by <response>
-  // and that inside response, there is a block opened by tag <chrome_config>
-  // other tags are ignored for now except the content of <chrome_config>.
-  VLOG(1) << "METRICS: getting settings from response data: " << data;
-
-  int data_size = static_cast<int>(data.size());
-  if (data_size < 0) {
-    VLOG(1) << "METRICS: server response data bad size: " << data_size
-            << "; aborting extraction of settings";
-    return;
-  }
-  xmlDocPtr doc = xmlReadMemory(data.c_str(), data_size, "", NULL, 0);
-  // If the document is malformed, we just use the settings that were there.
-  if (!doc) {
-    VLOG(1) << "METRICS: reading xml from server response data failed";
-    return;
-  }
-
-  xmlNodePtr top_node = xmlDocGetRootElement(doc), chrome_config_node = NULL;
-  // Here, we find the chrome_config node by name.
-  for (xmlNodePtr p = top_node->children; p; p = p->next) {
-    if (xmlStrEqual(p->name, BAD_CAST "chrome_config")) {
-      chrome_config_node = p;
-      break;
-    }
-  }
-  // If the server data is formatted wrong and there is no
-  // config node where we expect, we just drop out.
-  if (chrome_config_node != NULL)
-    GetSettingsFromChromeConfigNode(chrome_config_node);
-  xmlFreeDoc(doc);
-}
-
-void MetricsService::GetSettingsFromChromeConfigNode(
-    xmlNodePtr chrome_config_node) {
-  // Iterate through all children of the config node.
-  for (xmlNodePtr current_node = chrome_config_node->children;
-       current_node;
-       current_node = current_node->next) {
-    // If we find the upload tag, we appeal to another function
-    // GetSettingsFromUploadNode to read all the data in it.
-    if (xmlStrEqual(current_node->name, BAD_CAST "upload")) {
-      GetSettingsFromUploadNode(current_node);
-      continue;
-    }
-  }
-}
-
-void MetricsService::InheritedProperties::OverwriteWhereNeeded(
-    xmlNodePtr node) {
-  xmlChar* salt_value = xmlGetProp(node, BAD_CAST "salt");
-  if (salt_value)  // If the property isn't there, xmlGetProp returns NULL.
-      salt = atoi(reinterpret_cast<char*>(salt_value));
-  // If the property isn't there, we keep the value the property had before
-
-  xmlChar* denominator_value = xmlGetProp(node, BAD_CAST "denominator");
-  if (denominator_value)
-     denominator = atoi(reinterpret_cast<char*>(denominator_value));
-}
-
-void MetricsService::GetSettingsFromUploadNode(xmlNodePtr upload_node) {
-  InheritedProperties props;
-  GetSettingsFromUploadNodeRecursive(upload_node, props, "", true);
-}
-
-void MetricsService::GetSettingsFromUploadNodeRecursive(
-    xmlNodePtr node,
-    InheritedProperties props,
-    const std::string& path_prefix,
-    bool uploadOn) {
-  props.OverwriteWhereNeeded(node);
-
-  // The bool uploadOn is set to true if the data represented by current
-  // node should be uploaded. This gets inherited in the tree; the children
-  // of a node that has already been rejected for upload get rejected for
-  // upload.
-  uploadOn = uploadOn && NodeProbabilityTest(node, props);
-
-  // The path is a / separated list of the node names ancestral to the current
-  // one. So, if you want to check if the current node has a certain name,
-  // compare to name.  If you want to check if it is a certan tag at a certain
-  // place in the tree, compare to the whole path.
-  std::string name = std::string(reinterpret_cast<const char*>(node->name));
-  std::string path = path_prefix + "/" + name;
-
-  if (path == "/upload") {
-    xmlChar* upload_interval_val = xmlGetProp(node, BAD_CAST "interval");
-    if (upload_interval_val) {
-      interlog_duration_ = TimeDelta::FromSeconds(
-          atoi(reinterpret_cast<char*>(upload_interval_val)));
-    }
-
-    server_permits_upload_ = uploadOn;
-  } else if (path == "/upload/logs") {
-    xmlChar* log_event_limit_val = xmlGetProp(node, BAD_CAST "event_limit");
-    if (log_event_limit_val)
-      log_event_limit_ = atoi(reinterpret_cast<char*>(log_event_limit_val));
-  }
-
-  // Recursive call.  If the node is a leaf i.e. if it ends in a "/>", then it
-  // doesn't have children, so node->children is NULL, and this loop doesn't
-  // call (that's how the recursion ends).
-  for (xmlNodePtr child_node = node->children;
-       child_node;
-       child_node = child_node->next) {
-    GetSettingsFromUploadNodeRecursive(child_node, props, path, uploadOn);
-  }
-}
-
-bool MetricsService::NodeProbabilityTest(xmlNodePtr node,
-                                         InheritedProperties props) const {
-  // Default value of probability on any node is 1, but recall that
-  // its parents can already have been rejected for upload.
-  double probability = 1;
-
-  // If a probability is specified in the node, we use it instead.
-  xmlChar* probability_value = xmlGetProp(node, BAD_CAST "probability");
-  if (probability_value)
-    probability = atoi(reinterpret_cast<char*>(probability_value));
-
-  return ProbabilityTest(probability, props.salt, props.denominator);
-}
-
-bool MetricsService::ProbabilityTest(double probability,
-                                     int salt,
-                                     int denominator) const {
-  // Okay, first we figure out how many of the digits of the
-  // client_id_ we need in order to make a nice pseudorandomish
-  // number in the range [0,denominator).  Too many digits is
-  // fine.
-
-  // n is the length of the client_id_ string
-  size_t n = client_id_.size();
-
-  // idnumber is a positive integer generated from the client_id_.
-  // It plus salt is going to give us our pseudorandom number.
-  int idnumber = 0;
-  const char* client_id_c_str = client_id_.c_str();
-
-  // Here we hash the relevant digits of the client_id_
-  // string somehow to get a big integer idnumber (could be negative
-  // from wraparound)
-  int big = 1;
-  int last_pos = n - 1;
-  for (size_t j = 0; j < n; ++j) {
-    idnumber += static_cast<int>(client_id_c_str[last_pos - j]) * big;
-    big *= 10;
-  }
-
-  // Mod id number by denominator making sure to get a non-negative
-  // answer.
-  idnumber = ((idnumber % denominator) + denominator) % denominator;
-
-  // ((idnumber + salt) % denominator) / denominator is in the range [0,1]
-  // if it's less than probability we call that an affirmative coin
-  // toss.
-  return static_cast<double>((idnumber + salt) % denominator) <
-      probability * denominator;
-}
-
 void MetricsService::LogWindowChange(NotificationType type,
                                      const NotificationSource& source,
                                      const NotificationDetails& details) {
diff --git a/chrome/browser/metrics/metrics_service.h b/chrome/browser/metrics/metrics_service.h
index b2add89..922cf38 100644
--- a/chrome/browser/metrics/metrics_service.h
+++ b/chrome/browser/metrics/metrics_service.h
@@ -266,51 +266,6 @@ class MetricsService : public NotificationObserver,
   // a response code not equal to 200.
   void HandleBadResponseCode();
 
-  // Class to hold all attributes that gets inherited by children in the UMA
-  // response data xml tree.  This is to make it convenient in the
-  // recursive function that does the tree traversal to pass all such
-  // data in the recursive call.  If you want to add more such attributes,
-  // add them to this class.
-  class InheritedProperties {
-    public:
-    InheritedProperties() : salt(123123), denominator(1000000) {}
-    int salt, denominator;
-    // Notice salt and denominator are inherited from parent nodes, but
-    // not probability; the default value of probability is 1.
-
-    // When a new node is reached it might have fields which overwrite inherited
-    // properties for that node (and its children).  Call this method to
-    // overwrite those settings.
-    void OverwriteWhereNeeded(xmlNodePtr node);
-  };
-
-  // Called by OnURLFetchComplete with data as the argument
-  // parses the xml returned by the server in the call to OnURLFetchComplete
-  // and extracts settings for subsequent frequency and content of log posts.
-  void GetSettingsFromResponseData(const std::string& data);
-
-  // This is a helper function for GetSettingsFromResponseData which iterates
-  // through the xml tree at the level of the <chrome_config> node.
-  void GetSettingsFromChromeConfigNode(xmlNodePtr chrome_config_node);
-
-  // GetSettingsFromUploadNode handles iteration over the children of the
-  // <upload> child of the <chrome_config> node.  It calls the recursive
-  // function GetSettingsFromUploadNodeRecursive which does the actual
-  // tree traversal.
-  void GetSettingsFromUploadNode(xmlNodePtr upload_node);
-  void GetSettingsFromUploadNodeRecursive(xmlNodePtr node,
-      InheritedProperties props,
-      const std::string& path_prefix,
-      bool uploadOn);
-
-  // NodeProbabilityTest gets called at every node in the tree traversal
-  // performed by GetSettingsFromUploadNodeRecursive.  It determines from
-  // the inherited attributes (salt, denominator) and the probability
-  // assiciated with the node whether that node and its contents should
-  // contribute to the upload.
-  bool NodeProbabilityTest(xmlNodePtr node, InheritedProperties props) const;
-  bool ProbabilityTest(double probability, int salt, int denominator) const;
-
   // Records a window-related notification.
   void LogWindowChange(NotificationType type,
                        const NotificationSource& source,
@@ -458,11 +413,6 @@ class MetricsService : public NotificationObserver,
   // quickly transmit those unsent logs while we continue to build a log.
   base::TimeDelta interlog_duration_;
 
-  // The maximum number of events which get transmitted in a log.  This defaults
-  // to a constant and otherwise is provided by the UMA server in the server
-  // response data.
-  int log_event_limit_;
-
   // Indicate that a timer for sending the next log has already been queued.
   bool timer_pending_;