Merge "TypeHelpers.h: Don't underflow unsigned int"
diff --git a/init/compare-bootcharts.py b/init/compare-bootcharts.py
new file mode 100755
index 0000000..2057b55
--- /dev/null
+++ b/init/compare-bootcharts.py
@@ -0,0 +1,146 @@
+#!/usr/bin/env python
+
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Compare two bootcharts and list start/end timestamps on key processes.
+
+This script extracts two bootchart.tgz files and compares the timestamps
+in proc_ps.log for selected processes. The proc_ps.log file consists of
+repetitive blocks of the following format:
+
+timestamp1 (jiffies)
+dumps of /proc/<pid>/stat
+
+timestamp2
+dumps of /proc/<pid>/stat
+
+The timestamps are 200ms apart, and the creation time of selected processes
+are listed. The termination time of the boot animation process is also listed
+as a coarse indication about when the boot process is complete as perceived by
+the user.
+"""
+
+import sys
+import tarfile
+
+# The bootchart timestamps are 200ms apart, but the USER_HZ value is not
+# reported in the bootchart, so we use the first two timestamps to calculate
+# the wall clock time of a jiffy.
+jiffy_to_wallclock = {
+   '1st_timestamp': -1,
+   '2nd_timestamp': -1,
+   'jiffy_to_wallclock': -1
+}
+
+def analyze_process_maps(process_map1, process_map2, jiffy_record):
+    # List interesting processes here
+    processes_of_interest = [
+        '/init',
+        '/system/bin/surfaceflinger',
+        '/system/bin/bootanimation',
+        'zygote64',
+        'zygote',
+        'system_server'
+    ]
+
+    jw = jiffy_record['jiffy_to_wallclock']
+    print "process: baseline experiment (delta)"
+    print " - Unit is ms (a jiffy is %d ms on the system)" % jw
+    print "------------------------------------"
+    for p in processes_of_interest:
+        # e.g., 32-bit system doesn't have zygote64
+        if p in process_map1 and p in process_map2:
+            print "%s: %d %d (%+d)" % (
+                p, process_map1[p]['start_time'] * jw,
+                process_map2[p]['start_time'] * jw,
+                (process_map2[p]['start_time'] -
+                 process_map1[p]['start_time']) * jw)
+
+    # Print the last tick for the bootanimation process
+    print "bootanimation ends at: %d %d (%+d)" % (
+        process_map1['/system/bin/bootanimation']['last_tick'] * jw,
+        process_map2['/system/bin/bootanimation']['last_tick'] * jw,
+        (process_map2['/system/bin/bootanimation']['last_tick'] -
+            process_map1['/system/bin/bootanimation']['last_tick']) * jw)
+
+def parse_proc_file(pathname, process_map, jiffy_record=None):
+    # Uncompress bootchart.tgz
+    with tarfile.open(pathname + '/bootchart.tgz', 'r:*') as tf:
+        try:
+            # Read proc_ps.log
+            f = tf.extractfile('proc_ps.log')
+
+            # Break proc_ps into chunks based on timestamps
+            blocks = f.read().split('\n\n')
+            for b in blocks:
+                lines = b.split('\n')
+                if not lines[0]:
+                    break
+
+                # 200ms apart in jiffies
+                timestamp = int(lines[0]);
+
+                # Figure out the wall clock time of a jiffy
+                if jiffy_record is not None:
+                    if jiffy_record['1st_timestamp'] == -1:
+                        jiffy_record['1st_timestamp'] = timestamp
+                    elif jiffy_record['jiffy_to_wallclock'] == -1:
+                        # Not really needed but for debugging purposes
+                        jiffy_record['2nd_timestamp'] = timestamp
+                        value = 200 / (timestamp -
+                                       jiffy_record['1st_timestamp'])
+                        # Fix the rounding error
+                        # e.g., 201 jiffies in 200ms when USER_HZ is 1000
+                        if value == 0:
+                            value = 1
+                        # e.g., 21 jiffies in 200ms when USER_HZ is 100
+                        elif value == 9:
+                            value = 10
+                        jiffy_record['jiffy_to_wallclock'] = value
+
+                # Populate the process_map table
+                for line in lines[1:]:
+                    segs = line.split(' ')
+
+                    #  0: pid
+                    #  1: process name
+                    # 17: priority
+                    # 18: nice
+                    # 21: creation time
+
+                    proc_name = segs[1].strip('()')
+                    if proc_name in process_map:
+                        process = process_map[proc_name]
+                    else:
+                        process = {'start_time': int(segs[21])}
+                        process_map[proc_name] = process
+
+                    process['last_tick'] = timestamp
+        finally:
+            f.close()
+
+def main():
+    if len(sys.argv) != 3:
+        print "Usage: %s base_bootchart_dir exp_bootchart_dir" % sys.argv[0]
+        sys.exit(1)
+
+    process_map1 = {}
+    process_map2 = {}
+    parse_proc_file(sys.argv[1], process_map1, jiffy_to_wallclock)
+    parse_proc_file(sys.argv[2], process_map2)
+    analyze_process_maps(process_map1, process_map2, jiffy_to_wallclock)
+
+if __name__ == "__main__":
+    main()
diff --git a/init/readme.txt b/init/readme.txt
index c213041..4cbe600 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -347,6 +347,29 @@
 actually started init.
 
 
+Comparing two bootcharts
+------------------------
+A handy script named compare-bootcharts.py can be used to compare the
+start/end time of selected processes. The aforementioned grab-bootchart.sh
+will leave a bootchart tarball named bootchart.tgz at /tmp/android-bootchart.
+If two such barballs are preserved on the host machine under different
+directories, the script can list the timestamps differences. For example:
+
+Usage: system/core/init/compare-bootcharts.py base_bootchart_dir
+       exp_bootchart_dir
+
+process: baseline experiment (delta)
+ - Unit is ms (a jiffy is 10 ms on the system)
+------------------------------------
+/init: 50 40 (-10)
+/system/bin/surfaceflinger: 4320 4470 (+150)
+/system/bin/bootanimation: 6980 6990 (+10)
+zygote64: 10410 10640 (+230)
+zygote: 10410 10640 (+230)
+system_server: 15350 15150 (-200)
+bootanimation ends at: 33790 31230 (-2560)
+
+
 Debugging init
 --------------
 By default, programs executed by init will drop stdout and stderr into
diff --git a/liblog/log_is_loggable.c b/liblog/log_is_loggable.c
index 2e09192..7a8e33f 100644
--- a/liblog/log_is_loggable.c
+++ b/liblog/log_is_loggable.c
@@ -15,41 +15,158 @@
 */
 
 #include <ctype.h>
+#include <pthread.h>
+#include <stdlib.h>
 #include <string.h>
-#include <sys/system_properties.h>
+#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
+#include <sys/_system_properties.h>
 
 #include <android/log.h>
 
-static int __android_log_level(const char *tag, int def)
+struct cache {
+    const prop_info *pinfo;
+    uint32_t serial;
+    char c;
+};
+
+static void refresh_cache(struct cache *cache, const char *key)
 {
+    uint32_t serial;
     char buf[PROP_VALUE_MAX];
 
-    if (!tag || !*tag) {
-        return def;
+    if (!cache->pinfo) {
+        cache->pinfo = __system_property_find(key);
+        if (!cache->pinfo) {
+            return;
+        }
     }
-    {
-        static const char log_namespace[] = "persist.log.tag.";
-        char key[sizeof(log_namespace) + strlen(tag)];
+    serial = __system_property_serial(cache->pinfo);
+    if (serial == cache->serial) {
+        return;
+    }
+    cache->serial = serial;
+    __system_property_read(cache->pinfo, 0, buf);
+    cache->c = buf[0];
+}
 
-        strcpy(key, log_namespace);
+static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+static int __android_log_level(const char *tag, int def)
+{
+    /* sizeof() is used on this array below */
+    static const char log_namespace[] = "persist.log.tag.";
+    static const size_t base_offset = 8; /* skip "persist." */
+    /* calculate the size of our key temporary buffer */
+    const size_t taglen = (tag && *tag) ? strlen(tag) : 0;
+    /* sizeof(log_namespace) = strlen(log_namespace) + 1 */
+    char key[sizeof(log_namespace) + taglen];
+    char *kp;
+    size_t i;
+    char c = 0;
+    /*
+     * Single layer cache of four properties. Priorities are:
+     *    log.tag.<tag>
+     *    persist.log.tag.<tag>
+     *    log.tag
+     *    persist.log.tag
+     * Where the missing tag matches all tags and becomes the
+     * system global default. We do not support ro.log.tag* .
+     */
+    static char *last_tag;
+    static uint32_t global_serial;
+    uint32_t current_global_serial;
+    static struct cache tag_cache[2] = {
+        { NULL, -1, 0 },
+        { NULL, -1, 0 }
+    };
+    static struct cache global_cache[2] = {
+        { NULL, -1, 0 },
+        { NULL, -1, 0 }
+    };
+
+    strcpy(key, log_namespace);
+
+    pthread_mutex_lock(&lock);
+
+    current_global_serial = __system_property_area_serial();
+
+    if (taglen) {
+        uint32_t current_local_serial = current_global_serial;
+
+        if (!last_tag || strcmp(last_tag, tag)) {
+            /* invalidate log.tag.<tag> cache */
+            for(i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
+                tag_cache[i].pinfo = NULL;
+                tag_cache[i].serial = -1;
+                tag_cache[i].c = '\0';
+            }
+            free(last_tag);
+            last_tag = NULL;
+            current_global_serial = -1;
+        }
+        if (!last_tag) {
+            last_tag = strdup(tag);
+        }
         strcpy(key + sizeof(log_namespace) - 1, tag);
 
-        if (__system_property_get(key + 8, buf) <= 0) {
-            buf[0] = '\0';
-        }
-        if (!buf[0] && __system_property_get(key, buf) <= 0) {
-            buf[0] = '\0';
+        kp = key;
+        for(i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
+            if (current_local_serial != global_serial) {
+                refresh_cache(&tag_cache[i], kp);
+            }
+
+            if (tag_cache[i].c) {
+                c = tag_cache[i].c;
+                break;
+            }
+
+            kp = key + base_offset;
         }
     }
-    switch (toupper(buf[0])) {
-        case 'V': return ANDROID_LOG_VERBOSE;
-        case 'D': return ANDROID_LOG_DEBUG;
-        case 'I': return ANDROID_LOG_INFO;
-        case 'W': return ANDROID_LOG_WARN;
-        case 'E': return ANDROID_LOG_ERROR;
-        case 'F': /* FALLTHRU */ /* Not officially supported */
-        case 'A': return ANDROID_LOG_FATAL;
-        case 'S': return -1; /* ANDROID_LOG_SUPPRESS */
+
+    switch (toupper(c)) { /* if invalid, resort to global */
+    case 'V':
+    case 'D':
+    case 'I':
+    case 'W':
+    case 'E':
+    case 'F': /* Not officially supported */
+    case 'A':
+    case 'S':
+        break;
+    default:
+        /* clear '.' after log.tag */
+        key[sizeof(log_namespace) - 2] = '\0';
+
+        kp = key;
+        for(i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
+            if (current_global_serial != global_serial) {
+                refresh_cache(&global_cache[i], kp);
+            }
+
+            if (global_cache[i].c) {
+                c = global_cache[i].c;
+                break;
+            }
+
+            kp = key + base_offset;
+        }
+        break;
+    }
+
+    global_serial = current_global_serial;
+
+    pthread_mutex_unlock(&lock);
+
+    switch (toupper(c)) {
+    case 'V': return ANDROID_LOG_VERBOSE;
+    case 'D': return ANDROID_LOG_DEBUG;
+    case 'I': return ANDROID_LOG_INFO;
+    case 'W': return ANDROID_LOG_WARN;
+    case 'E': return ANDROID_LOG_ERROR;
+    case 'F': /* FALLTHRU */ /* Not officially supported */
+    case 'A': return ANDROID_LOG_FATAL;
+    case 'S': return -1; /* ANDROID_LOG_SUPPRESS */
     }
     return def;
 }
diff --git a/liblog/tests/Android.mk b/liblog/tests/Android.mk
index d75bbc9..a407c50 100644
--- a/liblog/tests/Android.mk
+++ b/liblog/tests/Android.mk
@@ -77,6 +77,6 @@
 LOCAL_MODULE := $(test_module_prefix)unit-tests
 LOCAL_MODULE_TAGS := $(test_tags)
 LOCAL_CFLAGS += $(test_c_flags)
-LOCAL_SHARED_LIBRARIES := liblog
+LOCAL_SHARED_LIBRARIES := liblog libcutils
 LOCAL_SRC_FILES := $(test_src_files)
 include $(BUILD_NATIVE_TEST)
diff --git a/liblog/tests/liblog_test.cpp b/liblog/tests/liblog_test.cpp
index 33f6481..abe0239 100644
--- a/liblog/tests/liblog_test.cpp
+++ b/liblog/tests/liblog_test.cpp
@@ -17,6 +17,8 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <signal.h>
+
+#include <cutils/properties.h>
 #include <gtest/gtest.h>
 #include <log/log.h>
 #include <log/logger.h>
@@ -439,6 +441,7 @@
 
     LOG_FAILURE_RETRY(__android_log_buf_write(LOG_ID_SYSTEM, ANDROID_LOG_INFO,
                                               tag, max_payload_buf));
+    sleep(2);
 
     struct logger_list *logger_list;
 
@@ -603,10 +606,14 @@
         if (id != android_name_to_log_id(name)) {
             continue;
         }
+        fprintf(stderr, "log buffer %s\r", name);
         struct logger * logger;
         EXPECT_TRUE(NULL != (logger = android_logger_open(logger_list, id)));
         EXPECT_EQ(id, android_logger_get_id(logger));
-        EXPECT_LT(0, android_logger_get_log_size(logger));
+        /* crash buffer is allowed to be empty, that is actually healthy! */
+        if (android_logger_get_log_size(logger) || strcmp("crash", name)) {
+            EXPECT_LT(0, android_logger_get_log_size(logger));
+        }
         EXPECT_LT(0, android_logger_get_log_readable_size(logger));
         EXPECT_LT(0, android_logger_get_log_version(logger));
     }
@@ -682,3 +689,190 @@
 
     android_log_format_free(p_format);
 }
+
+TEST(liblog, is_loggable) {
+    static const char tag[] = "is_loggable";
+    static const char log_namespace[] = "persist.log.tag.";
+    static const size_t base_offset = 8; /* skip "persist." */
+    // sizeof("string") = strlen("string") + 1
+    char key[sizeof(log_namespace) + sizeof(tag) - 1];
+    char hold[4][PROP_VALUE_MAX];
+    static const struct {
+        int level;
+        char type;
+    } levels[] = {
+        { ANDROID_LOG_VERBOSE, 'v' },
+        { ANDROID_LOG_DEBUG  , 'd' },
+        { ANDROID_LOG_INFO   , 'i' },
+        { ANDROID_LOG_WARN   , 'w' },
+        { ANDROID_LOG_ERROR  , 'e' },
+        { ANDROID_LOG_FATAL  , 'a' },
+        { -1                 , 's' },
+        { -2                 , 'g' }, // Illegal value, resort to default
+    };
+
+    // Set up initial test condition
+    memset(hold, 0, sizeof(hold));
+    snprintf(key, sizeof(key), "%s%s", log_namespace, tag);
+    property_get(key, hold[0], "");
+    property_set(key, "");
+    property_get(key + base_offset, hold[1], "");
+    property_set(key + base_offset, "");
+    strcpy(key, log_namespace);
+    key[sizeof(log_namespace) - 2] = '\0';
+    property_get(key, hold[2], "");
+    property_set(key, "");
+    property_get(key, hold[3], "");
+    property_set(key + base_offset, "");
+
+    // All combinations of level and defaults
+    for(size_t i = 0; i < (sizeof(levels) / sizeof(levels[0])); ++i) {
+        if (levels[i].level == -2) {
+            continue;
+        }
+        for(size_t j = 0; j < (sizeof(levels) / sizeof(levels[0])); ++j) {
+            if (levels[j].level == -2) {
+                continue;
+            }
+            fprintf(stderr, "i=%zu j=%zu\r", i, j);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       levels[j].level));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      levels[j].level));
+            }
+        }
+    }
+
+    // All combinations of level and tag and global properties
+    for(size_t i = 0; i < (sizeof(levels) / sizeof(levels[0])); ++i) {
+        if (levels[i].level == -2) {
+            continue;
+        }
+        for(size_t j = 0; j < (sizeof(levels) / sizeof(levels[0])); ++j) {
+            char buf[2];
+            buf[0] = levels[j].type;
+            buf[1] = '\0';
+
+            snprintf(key, sizeof(key), "%s%s", log_namespace, tag);
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key, buf);
+            property_set(key, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_DEBUG)
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key, "");
+
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key + base_offset, buf);
+            property_set(key + base_offset, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_DEBUG)
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key + base_offset, "");
+
+            strcpy(key, log_namespace);
+            key[sizeof(log_namespace) - 2] = '\0';
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key, buf);
+            property_set(key, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_DEBUG)
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key, "");
+
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key + base_offset, buf);
+            property_set(key + base_offset, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_DEBUG)
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key + base_offset, "");
+        }
+    }
+
+    // All combinations of level and tag properties, but with global set to INFO
+    strcpy(key, log_namespace);
+    key[sizeof(log_namespace) - 2] = '\0';
+    property_set(key, "I");
+    snprintf(key, sizeof(key), "%s%s", log_namespace, tag);
+    for(size_t i = 0; i < (sizeof(levels) / sizeof(levels[0])); ++i) {
+        if (levels[i].level == -2) {
+            continue;
+        }
+        for(size_t j = 0; j < (sizeof(levels) / sizeof(levels[0])); ++j) {
+            char buf[2];
+            buf[0] = levels[j].type;
+            buf[1] = '\0';
+
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key, buf);
+            property_set(key, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_INFO) // Yes INFO
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key, "");
+
+            fprintf(stderr, "i=%zu j=%zu property_set(\"%s\",\"%s\")\r",
+                    i, j, key + base_offset, buf);
+            property_set(key + base_offset, buf);
+            if ((levels[i].level < levels[j].level)
+                    || (levels[j].level == -1)
+                    || ((levels[i].level < ANDROID_LOG_INFO) // Yes INFO
+                        && (levels[j].level == -2))) {
+                EXPECT_FALSE(__android_log_is_loggable(levels[i].level, tag,
+                                                       ANDROID_LOG_DEBUG));
+            } else {
+                EXPECT_TRUE(__android_log_is_loggable(levels[i].level, tag,
+                                                      ANDROID_LOG_DEBUG));
+            }
+            property_set(key + base_offset, "");
+        }
+    }
+
+    // reset parms
+    snprintf(key, sizeof(key), "%s%s", log_namespace, tag);
+    property_set(key, hold[0]);
+    property_set(key + base_offset, hold[1]);
+    strcpy(key, log_namespace);
+    key[sizeof(log_namespace) - 2] = '\0';
+    property_set(key, hold[2]);
+    property_set(key + base_offset, hold[3]);
+}
diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index 4373e2a..0f5071b 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -140,8 +140,26 @@
     if ((log_id >= LOG_ID_MAX) || (log_id < 0)) {
         return -EINVAL;
     }
+
     LogBufferElement *elem = new LogBufferElement(log_id, realtime,
                                                   uid, pid, tid, msg, len);
+    int prio = ANDROID_LOG_INFO;
+    const char *tag = NULL;
+    if (log_id == LOG_ID_EVENTS) {
+        tag = android::tagToName(elem->getTag());
+    } else {
+        prio = *msg;
+        tag = msg + 1;
+    }
+    if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {
+        // Log traffic received to total
+        pthread_mutex_lock(&mLogElementsLock);
+        stats.add(elem);
+        stats.subtract(elem);
+        pthread_mutex_unlock(&mLogElementsLock);
+        delete elem;
+        return -EACCES;
+    }
 
     pthread_mutex_lock(&mLogElementsLock);
 
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index 8238a52..7df1123 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -105,8 +105,12 @@
 size_t LogBufferElement::populateDroppedMessage(char *&buffer,
         LogBuffer *parent) {
     static const char tag[] = "chatty";
-    static const char format_uid[] = "uid=%u%s%s expire %u line%s";
 
+    if (!__android_log_is_loggable(ANDROID_LOG_INFO, tag, ANDROID_LOG_VERBOSE)) {
+        return 0;
+    }
+
+    static const char format_uid[] = "uid=%u%s%s expire %u line%s";
     char *name = parent->uidToName(mUid);
     char *commName = android::tidToName(mTid);
     if (!commName && (mTid != mPid)) {