logd: Add support for *.logd.filter

- Add device (ro.logd.filter), persistent (persist.logd.filter)
  properties to control the default filters
- Allow logcat -P default to produce expected results
- Allow logcat -P disable to produce expected results

Change-Id: I651cb705373ec1e88a99e4b9086da4f9668a468a

logd/LogWhiteBlackList.cpp

@@ -17,6 +17,7 @@
 #include <ctype.h>
 
 #include <base/stringprintf.h>
+#include <cutils/properties.h>
 
 #include "LogWhiteBlackList.h"
 
@@ -49,7 +50,8 @@ std::string Prune::format() {
     return std::string("/");
 }
 
-PruneList::PruneList() : mWorstUidEnabled(true) {
+PruneList::PruneList() {
+    init(NULL);
 }
 
 PruneList::~PruneList() {
@@ -72,13 +74,44 @@ int PruneList::init(const char *str) {
         it = mNaughty.erase(it);
     }
 
-    if (!str) {
-        return 0;
+    static const char _default[] = "default";
+    // default here means take ro.logd.filter, persist.logd.filter then
+    // internal default in that order.
+    if (str && !strcmp(str, _default)) {
+        str = NULL;
+    }
+    static const char _disable[] = "disable";
+    if (str && !strcmp(str, _disable)) {
+        str = "";
+    }
+
+    std::string filter;
+
+    if (str) {
+        filter = str;
+    } else {
+        char property[PROPERTY_VALUE_MAX];
+        property_get("ro.logd.filter", property, _default);
+        filter = property;
+        property_get("persist.logd.filter", property, filter.c_str());
+        // default here means take ro.logd.filter
+        if (strcmp(property, _default)) {
+            filter = property;
+        }
+    }
+
+    // default here means take internal default.
+    if (filter == _default) {
+        // See README.property for description of filter format
+        filter = "~!";
+    }
+    if (filter == _disable) {
+        filter = "";
     }
 
     mWorstUidEnabled = false;
 
-    for(; *str; ++str) {
+    for(str = filter.c_str(); *str; ++str) {
         if (isspace(*str)) {
             continue;
         }

logd/README.property

@@ -12,16 +12,24 @@ ro.build.type               string       if user, logd.statistics & logd.klogd
                                          default false
 persist.logd.logpersistd    string       Enable logpersist daemon, "logcatd"
                                          turns on logcat -f in logd context
-persist.logd.size          number 256K   default size of the buffer for all
-                                         log ids at initial startup, at runtime
-                                         use: logcat -b all -G <value>
+persist.logd.size          number 256K   Global default size of the buffer for
+                                         all log ids at initial startup, at
+                                         runtime use: logcat -b all -G <value>
 persist.logd.size.main     number 256K   Size of the buffer for the main log
 persist.logd.size.system   number 256K   Size of the buffer for the system log
 persist.logd.size.radio    number 256K   Size of the buffer for the radio log
 persist.logd.size.event    number 256K   Size of the buffer for the event log
 persist.logd.size.crash    number 256K   Size of the buffer for the crash log
+persist.logd.filter         string       Pruning filter to optimize content,
+                                         default is ro.logd.filter or
+                                         "~!" which means to prune the oldest
+                                         entries of chattiest UID. At runtime
+                                         use: logcat -P "<string>"
 
 NB:
-- number support multipliers (K or M) for convenience. Range is limited
-  to between 64K and 256M for log buffer sizes. Individual logs override the
-  global default.
+- Number support multipliers (K or M) for convenience. Range is limited
+  to between 64K and 256M for log buffer sizes. Individual log buffer ids
+  such as main, system, ... override global default.
+- Pruning filter is of form of a space-separated list of [~][UID][/PID]
+  references, where '~' prefix means to blacklist otherwise whitelist. For
+  blacklisting, UID may be a '!' to instead reference the chattiest client.

logd/main.cpp

@@ -212,6 +212,7 @@ static void *reinit_thread_start(void * /*obj*/) {
         // Anything that reads persist.<property>
         if (logBuf) {
             logBuf->init();
+            logBuf->initPrune(NULL);
         }
     }