commit ad5e411608a503a6a27c1e0515e1a0272c320bf2
author Mark Salyzyn <salyzyn@google.com> Thu Aug 04 07:53:52 2016 -0700
committer Mark Salyzyn <salyzyn@google.com> Mon Aug 08 10:20:22 2016 -0700
tree 7ab396393299dc694d3368725671e16c2c867cc4
parent 31961061d5c483596616afaa69b33f77fea5ff97

logcat: -d, -t or -L, along with -f, do not background

Specifically logcatd with exec logcat -L needs to be foreground
process cgroup as it is spawned and can block init progress. Makes
sense generally to only set background cgroup when we are taking
continuous content, and we are pushing that content to a set of
logrotate files.

Rename setupOutput to setupOutputAndSchedulingPolicy to more
clearly indicate its purpose.

Bug: 30630936
Bug: 30612424
Bug: 28788401
Change-Id: I628d590a42a53a6b448ecd0af53d6d1edf7bbb0e

logcat/logcat.cpp

diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index b761dd3..7e2bac7 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -230,13 +230,15 @@
     }
 }
 
-static void setupOutput()
-{
-
+static void setupOutputAndSchedulingPolicy(bool blocking) {
     if (g_outputFileName == NULL) {
         g_outFD = STDOUT_FILENO;
+        return;
+    }
 
-    } else {
+    if (blocking) {
+        // Lower priority and set to batch scheduling if we are saving
+        // the logs into files and taking continuous content.
         if (set_sched_policy(0, SP_BACKGROUND) < 0) {
             fprintf(stderr, "failed to set background scheduling policy\n");
         }
@@ -250,26 +252,26 @@
         if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) {
             fprintf(stderr, "failed set to priority\n");
         }
-
-        g_outFD = openLogFile (g_outputFileName);
-
-        if (g_outFD < 0) {
-            logcat_panic(false, "couldn't open output file");
-        }
-
-        struct stat statbuf;
-        if (fstat(g_outFD, &statbuf) == -1) {
-            close(g_outFD);
-            logcat_panic(false, "couldn't get output file stat\n");
-        }
-
-        if ((size_t) statbuf.st_size > SIZE_MAX || statbuf.st_size < 0) {
-            close(g_outFD);
-            logcat_panic(false, "invalid output file stat\n");
-        }
-
-        g_outByteCount = statbuf.st_size;
     }
+
+    g_outFD = openLogFile (g_outputFileName);
+
+    if (g_outFD < 0) {
+        logcat_panic(false, "couldn't open output file");
+    }
+
+    struct stat statbuf;
+    if (fstat(g_outFD, &statbuf) == -1) {
+        close(g_outFD);
+        logcat_panic(false, "couldn't get output file stat\n");
+    }
+
+    if ((size_t) statbuf.st_size > SIZE_MAX || statbuf.st_size < 0) {
+        close(g_outFD);
+        logcat_panic(false, "invalid output file stat\n");
+    }
+
+    g_outByteCount = statbuf.st_size;
 }
 
 static void show_help(const char *cmd)
@@ -659,7 +661,7 @@
             break;
 
             case 'L':
-                mode |= ANDROID_LOG_PSTORE;
+                mode |= ANDROID_LOG_RDONLY | ANDROID_LOG_PSTORE | ANDROID_LOG_NONBLOCK;
             break;
 
             case 'd':
@@ -1201,7 +1203,7 @@
         return EXIT_SUCCESS;
     }
 
-    setupOutput(mode);
+    setupOutputAndSchedulingPolicy((mode & ANDROID_LOG_NONBLOCK) == 0);
 
     //LOG_EVENT_INT(10, 12345);
     //LOG_EVENT_LONG(11, 0x1122334455667788LL);