logd: Add control statistics enable/disable.

- ro.build.type=user turn off statistics
- ro.config.low_ram=true turn off statistics
- logd.statistics override

(cherry pick from commit f5fc509589)

Bug: 17526159
Bug: 17526187
Change-Id: I74796043ac34753c6dd10018719ebc0bcd94e00f

logd/LogBuffer.h

@@ -68,6 +68,10 @@ public:
         dgramQlenStatistics = true;
     }
 
+    void enableStatistics() {
+        stats.enableStatistics();
+    }
+
     int initPrune(char *cp) { return mPrune.init(cp); }
     // *strp uses malloc, use free to release.
     void formatPrune(char **strp) { mPrune.format(strp); }

logd/LogStatistics.cpp

@@ -384,7 +384,8 @@ size_t LidStatistics::elementsTotal(uid_t uid, pid_t pid) {
 }
 
 LogStatistics::LogStatistics()
-        : dgramQlenStatistics(false)
+        : mStatistics(false)
+        , dgramQlenStatistics(false)
         , start(CLOCK_MONOTONIC) {
     log_id_for_each(i) {
         mSizes[i] = 0;
@@ -455,6 +456,9 @@ void LogStatistics::add(unsigned short size,
                         log_id_t log_id, uid_t uid, pid_t pid) {
     mSizes[log_id] += size;
     ++mElements[log_id];
+    if (!mStatistics) {
+        return;
+    }
     id(log_id).add(size, uid, pid);
 }
 
@@ -462,6 +466,9 @@ void LogStatistics::subtract(unsigned short size,
                              log_id_t log_id, uid_t uid, pid_t pid) {
     mSizes[log_id] -= size;
     --mElements[log_id];
+    if (!mStatistics) {
+        return;
+    }
     id(log_id).subtract(size, uid, pid);
 }
 
@@ -545,25 +552,28 @@ void LogStatistics::format(char **buf,
 
     spaces = 1;
     log_time t(CLOCK_MONOTONIC);
-    unsigned long long d = t.nsec() - start.nsec();
-    string.appendFormat("\nTotal%4llu:%02llu:%02llu.%09llu",
+    unsigned long long d;
+    if (mStatistics) {
+        d = t.nsec() - start.nsec();
+        string.appendFormat("\nTotal%4llu:%02llu:%02llu.%09llu",
                   d / NS_PER_SEC / 60 / 60, (d / NS_PER_SEC / 60) % 60,
                   (d / NS_PER_SEC) % 60, d % NS_PER_SEC);
 
-    log_id_for_each(i) {
-        if (!(logMask & (1 << i))) {
-            continue;
+        log_id_for_each(i) {
+            if (!(logMask & (1 << i))) {
+                continue;
+            }
+            oldLength = string.length();
+            if (spaces < 0) {
+                spaces = 0;
+            }
+            string.appendFormat("%*s%zu/%zu", spaces, "",
+                                sizesTotal(i), elementsTotal(i));
+            spaces += spaces_total + oldLength - string.length();
         }
-        oldLength = string.length();
-        if (spaces < 0) {
-            spaces = 0;
-        }
-        string.appendFormat("%*s%zu/%zu", spaces, "",
-                            sizesTotal(i), elementsTotal(i));
-        spaces += spaces_total + oldLength - string.length();
+        spaces = 1;
     }
 
-    spaces = 1;
     d = t.nsec() - oldest.nsec();
     string.appendFormat("\nNow%6llu:%02llu:%02llu.%09llu",
                   d / NS_PER_SEC / 60 / 60, (d / NS_PER_SEC / 60) % 60,

logd/LogStatistics.h

@@ -144,6 +144,7 @@ class LogStatistics {
     size_t mSizes[LOG_ID_MAX];
     size_t mElements[LOG_ID_MAX];
 
+    bool mStatistics;
     bool dgramQlenStatistics;
 
     static const unsigned short mBuckets[14];
@@ -157,6 +158,7 @@ public:
     LidStatistics &id(log_id_t log_id) { return LogIds[log_id]; }
 
     void enableDgramQlenStatistics() { dgramQlenStatistics = true; }
+    void enableStatistics() { mStatistics = true; }
     static unsigned short dgramQlen(unsigned short bucket);
     unsigned long long minimum(unsigned short bucket);
     void recordDiff(log_time diff, unsigned short bucket);

logd/README.property

@@ -4,6 +4,9 @@ name                       type default  description
 logd.auditd                 bool  true   Enable selinux audit daemon
 logd.auditd.dmesg           bool  true   selinux audit messages duplicated and
                                          sent on to dmesg log
+logd.statistics             bool depends Enable logcat -S statistics.
+ro.config.low_ram           bool  false  if true, logd.statistics default false
+ro.build.type               string       if user, logd.statistics default false
 logd.statistics.dgram_qlen  bool  false  Record dgram_qlen statistics. This
                                          represents a performance impact and
                                          is used to determine the platform's

logd/main.cpp

@@ -152,6 +152,15 @@ int main() {
     if (property_get_bool("logd.statistics.dgram_qlen", false)) {
         logBuf->enableDgramQlenStatistics();
     }
+    {
+        char property[PROPERTY_VALUE_MAX];
+        property_get("ro.build.type", property, "");
+        if (property_get_bool("logd.statistics",
+                   !!strcmp(property, "user")
+                && !property_get_bool("ro.config.low_ram", false))) {
+            logBuf->enableStatistics();
+        }
+    }
 
     // LogReader listens on /dev/socket/logdr. When a client
     // connects, log entries in the LogBuffer are written to the client.