logd: Add Tag statistics

(cherry pick from commit 344bff4391dd434dda501e812f18f524290c5a7c)

- Optional class of statistics for events Tags
- export tagToName from LogBuffer (located in main.cp to address
  https://android-review.googlesource.com/#/c/110204)
- Can not handle dropped because getTag() can not work,
  will need to be fixed if we start filtering.

Bug: 19608965
Change-Id: I7b90607ca588bf37bab71f19b1570a290e772776

5 files changed, 110 insertions, 2 deletions

diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 6a057000d..164faa9f8 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -50,6 +50,13 @@ LogBufferElement::~LogBufferElement() {
     delete [] mMsg;
 }
 
+uint32_t LogBufferElement::getTag() const {
+    if ((mLogId != LOG_ID_EVENTS) || !mMsg || (mMsgLen < sizeof(uint32_t))) {
+        return 0;
+    }
+    return le32toh(reinterpret_cast<android_event_header_t *>(mMsg)->tag);
+}
+
 // caller must own and free character string
 static char *tidToName(pid_t tid) {
     char *retval = NULL;
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index b6c6196d2..75ec59e80 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -36,6 +36,9 @@ char *uidToName(uid_t uid);
 // Furnished in LogStatistics.cpp. Caller must own and free returned value
 char *pidToName(pid_t pid);
 
+// Furnished in main.cpp. Thread safe.
+const char *tagToName(uint32_t tag);
+
 }
 
 static inline bool worstUidEnabledForLogid(log_id_t id) {
@@ -85,6 +88,8 @@ public:
     static uint64_t getCurrentSequence(void) { return sequence.load(memory_order_relaxed); }
     log_time getRealTime(void) const { return mRealTime; }
 
+    uint32_t getTag(void) const;
+
     static const uint64_t FLUSH_ERROR;
     uint64_t flushTo(SocketClient *writer, LogBuffer *parent);
 };
diff --git a/logd/LogStatistics.cpp b/logd/LogStatistics.cpp
index 2eab4dd72..4511e0b8e 100644
--- a/logd/LogStatistics.cpp
+++ b/logd/LogStatistics.cpp
@@ -80,6 +80,11 @@ void LogStatistics::add(LogBufferElement *e) {
     }
 
     pidTable.add(e->getPid(), e);
+
+    uint32_t tag = e->getTag();
+    if (tag) {
+        tagTable.add(tag, e);
+    }
 }
 
 void LogStatistics::subtract(LogBufferElement *e) {
@@ -95,6 +100,11 @@ void LogStatistics::subtract(LogBufferElement *e) {
     }
 
     pidTable.subtract(e->getPid(), e);
+
+    uint32_t tag = e->getTag();
+    if (tag) {
+        tagTable.subtract(tag, e);
+    }
 }
 
 // Atomically set an entry to drop
@@ -373,6 +383,51 @@ void LogStatistics::format(char **buf, uid_t uid, unsigned int logMask) {
         }
     }
 
+    if (enable && (logMask & (1 << LOG_ID_EVENTS))) {
+        // Tag table
+        bool headerPrinted = false;
+        std::unique_ptr<const TagEntry *[]> sorted = tagTable.sort(maximum_sorted_entries);
+        ssize_t index = -1;
+        while ((index = tagTable.next(index, sorted, maximum_sorted_entries)) >= 0) {
+            const TagEntry *entry = sorted[index];
+            uid_t u = entry->getUid();
+            if ((uid != AID_ROOT) && (u != uid)) {
+                continue;
+            }
+
+            android::String8 pruned("");
+
+            if (!headerPrinted) {
+                output.appendFormat("\n\n");
+                android::String8 name("Chattiest events log buffer TAGs:");
+                android::String8 size("Size");
+                format_line(output, name, size, pruned);
+
+                name.setTo("    TAG/UID   TAGNAME");
+                size.setTo("BYTES");
+                format_line(output, name, size, pruned);
+
+                headerPrinted = true;
+            }
+
+            android::String8 name("");
+            if (u == (uid_t)-1) {
+                name.appendFormat("%7u", entry->getKey());
+            } else {
+                name.appendFormat("%7u/%u", entry->getKey(), u);
+            }
+            const char *n = entry->getName();
+            if (n) {
+                name.appendFormat("%*s%s", (int)std::max(14 - name.length(), (size_t)1), "", n);
+            }
+
+            android::String8 size("");
+            size.appendFormat("%zu", entry->getSizes());
+
+            format_line(output, name, size, pruned);
+        }
+    }
+
     *buf = strdup(output.string());
 }
 
diff --git a/logd/LogStatistics.h b/logd/LogStatistics.h
index ca4b9a6bf..d21a75bfe 100644
--- a/logd/LogStatistics.h
+++ b/logd/LogStatistics.h
@@ -154,8 +154,6 @@ struct UidEntry : public EntryBaseDropped {
 };
 
 namespace android {
-// caller must own and free character string
-char *pidToName(pid_t pid);
 uid_t pidToUid(pid_t pid);
 }
 
@@ -209,7 +207,28 @@ struct PidEntry : public EntryBaseDropped {
         }
         EntryBaseDropped::add(e);
     }
+};
+
+struct TagEntry : public EntryBase {
+    const uint32_t tag;
+    uid_t uid;
+
+    TagEntry(LogBufferElement *e):
+        EntryBase(e),
+        tag(e->getTag()),
+        uid(e->getUid()) { }
+
+    const uint32_t&getKey() const { return tag; }
+    const uid_t&getUid() const { return uid; }
+    const char*getName() const { return android::tagToName(tag); }
 
+    inline void add(LogBufferElement *e) {
+        uid_t u = e->getUid();
+        if (uid != u) {
+            uid = -1;
+        }
+        EntryBase::add(e);
+    }
 };
 
 // Log Statistics
@@ -228,6 +247,10 @@ class LogStatistics {
     typedef LogHashtable<pid_t, PidEntry> pidTable_t;
     pidTable_t pidTable;
 
+    // tag list
+    typedef LogHashtable<uint32_t, TagEntry> tagTable_t;
+    tagTable_t tagTable;
+
 public:
     LogStatistics();
 
diff --git a/logd/main.cpp b/logd/main.cpp
index 237c7c1cf..7b8e94e66 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -35,6 +35,7 @@
 #include <cutils/properties.h>
 #include <cutils/sched_policy.h>
 #include <cutils/sockets.h>
+#include <log/event_tag_map.h>
 #include <private/android_filesystem_config.h>
 
 #include "CommandListener.h"
@@ -238,6 +239,23 @@ void reinit_signal_handler(int /*signal*/) {
     sem_post(&reinit);
 }
 
+// tagToName converts an events tag into a name
+const char *android::tagToName(uint32_t tag) {
+    static const EventTagMap *map;
+
+    if (!map) {
+        sem_wait(&sem_name);
+        if (!map) {
+            map = android_openEventTagMap(EVENT_TAG_MAP_FILE);
+        }
+        sem_post(&sem_name);
+        if (!map) {
+            return NULL;
+        }
+    }
+    return android_lookupEventTag(map, tag);
+}
+
 // Foreground waits for exit of the main persistent threads
 // that are started here. The threads are created to manage
 // UNIX domain client sockets for writing, reading and