Allow logging mechanism to be overridden by applications.

This necessitated the removal of gpr_vlog to keep a clean interface.
	Change on 2015/01/09 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=83634996

5 files changed, 114 insertions, 42 deletions

diff --git a/src/core/support/log.c b/src/core/support/log.c
index b9e2897efc..7f102efea8 100644
--- a/src/core/support/log.c
+++ b/src/core/support/log.c
@@ -34,6 +34,10 @@
 #include <grpc/support/log.h>
 
 #include <stdio.h>
+#include <string.h>
+
+extern void gpr_default_log(gpr_log_func_args *args);
+static gpr_log_func g_log_func = gpr_default_log;
 
 const char *gpr_log_severity_string(gpr_log_severity severity) {
   switch (severity) {
@@ -47,12 +51,15 @@ const char *gpr_log_severity_string(gpr_log_severity severity) {
   return "UNKNOWN";
 }
 
-void gpr_log(const char *file, int line, gpr_log_severity severity,
-             const char *format, ...) {
-  va_list args;
-  va_start(args, format);
-
-  gpr_vlog(file, line, severity, format, args);
-
-  va_end(args);
+void gpr_log_message(const char *file, int line, gpr_log_severity severity,
+                     const char *message) {
+  gpr_log_func_args lfargs;
+  memset(&lfargs, 0, sizeof(lfargs));
+  lfargs.file = file;
+  lfargs.line = line;
+  lfargs.severity = severity;
+  lfargs.message = message;
+  g_log_func(&lfargs);
 }
+
+void gpr_set_log_function(gpr_log_func f) { g_log_func = f; }
diff --git a/src/core/support/log_android.c b/src/core/support/log_android.c
index 4c83e09914..11129e3e06 100644
--- a/src/core/support/log_android.c
+++ b/src/core/support/log_android.c
@@ -54,25 +54,31 @@ static android_LogPriority severity_to_log_priority(gpr_log_severity severity) {
   return ANDROID_LOG_DEFAULT;
 }
 
-void gpr_vlog(const char *file, int line, gpr_log_severity severity,
-              const char *format, va_list args) {
+void gpr_log(const char *file, int line, gpr_log_severity severity,
+             const char *format, ...) {
+  char *message = NULL;
+  va_list args;
+  va_start(args, format);
+  vasprintf(&message, format, args);
+  va_end(args);
+  gpr_log_message(file, line, severity, message);
+  free(message);
+}
+
+void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
   const char *display_file;
-  char *prefix = NULL;
-  char *suffix = NULL;
   char *output = NULL;
 
-  final_slash = strrchr(file, '/');
+  final_slash = strrchr(args->file, '/');
   if (final_slash == NULL)
     display_file = file;
   else
     display_file = final_slash + 1;
 
-  asprintf(&prefix, "%s:%d] ", display_file, line);
-  vasprintf(&suffix, format, args);
-  asprintf(&output, "%s%s", prefix, suffix);
+  asprintf(&prefix, "%s:%d] %s", display_file, args->line, args->message);
 
-  __android_log_write(severity_to_log_priority(severity), "GRPC", output);
+  __android_log_write(severity_to_log_priority(args->severity), "GRPC", output);
 
   /* allocated by asprintf => use free, not gpr_free */
   free(prefix);
diff --git a/src/core/support/log_linux.c b/src/core/support/log_linux.c
index 322ff07dd9..f3b528bdc4 100644
--- a/src/core/support/log_linux.c
+++ b/src/core/support/log_linux.c
@@ -49,17 +49,27 @@
 
 static long gettid() { return syscall(__NR_gettid); }
 
-void gpr_vlog(const char *file, int line, gpr_log_severity severity,
-              const char *format, va_list args) {
+void gpr_log(const char *file, int line, gpr_log_severity severity,
+             const char *format, ...) {
+  char *message = NULL;
+  va_list args;
+  va_start(args, format);
+  vasprintf(&message, format, args);
+  va_end(args);
+  gpr_log_message(file, line, severity, message);
+  free(message);
+}
+
+void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
   const char *display_file;
   char time_buffer[64];
   gpr_timespec now = gpr_now();
   struct tm tm;
 
-  final_slash = strrchr(file, '/');
+  final_slash = strrchr(args->file, '/');
   if (final_slash == NULL)
-    display_file = file;
+    display_file = args->file;
   else
     display_file = final_slash + 1;
 
@@ -70,12 +80,10 @@ void gpr_vlog(const char *file, int line, gpr_log_severity severity,
     strcpy(time_buffer, "error:strftime");
   }
 
-  flockfile(stderr);
-  fprintf(stderr, "%s%s.%09d %7ld %s:%d] ", gpr_log_severity_string(severity),
-          time_buffer, (int)(now.tv_nsec), gettid(), display_file, line);
-  vfprintf(stderr, format, args);
-  fputc('\n', stderr);
-  funlockfile(stderr);
+  fprintf(stderr, "%s%s.%09d %7ld %s:%d] %s\n",
+          gpr_log_severity_string(args->severity), time_buffer,
+          (int)(now.tv_nsec), gettid(), display_file, args->line,
+          args->message);
 }
 
 #endif
diff --git a/src/core/support/log_posix.c b/src/core/support/log_posix.c
index b47c433cd7..0420570a3e 100644
--- a/src/core/support/log_posix.c
+++ b/src/core/support/log_posix.c
@@ -47,17 +47,40 @@
 
 static long gettid() { return pthread_self(); }
 
-void gpr_vlog(const char *file, int line, gpr_log_severity severity,
-              const char *format, va_list args) {
+void gpr_log(const char *file, int line, gpr_log_severity severity,
+             const char *format, ...) {
+  char buf[64];
+  char *allocated = NULL;
+  char *message = NULL;
+  int ret;
+  va_list args;
+  va_start(args, format);
+  ret = vsnprintf(buf, format, args);
+  va_end(args);
+  if (ret < 0) {
+    message = NULL;
+  } else if (ret <= sizeof(buf) - 1) {
+    message = buf;
+  } else {
+    message = allocated = gpr_malloc(ret + 1);
+    va_start(args, format);
+    vsnprintf(message, format, args);
+    va_end(args);
+  }
+  gpr_log_message(file, line, severity, message);
+  gpr_free(allocated);
+}
+
+void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
   const char *display_file;
   char time_buffer[64];
   gpr_timespec now = gpr_now();
   struct tm tm;
 
-  final_slash = strrchr(file, '/');
+  final_slash = strrchr(args->file, '/');
   if (final_slash == NULL)
-    display_file = file;
+    display_file = args->file;
   else
     display_file = final_slash + 1;
 
@@ -68,12 +91,10 @@ void gpr_vlog(const char *file, int line, gpr_log_severity severity,
     strcpy(time_buffer, "error:strftime");
   }
 
-  flockfile(stderr);
-  fprintf(stderr, "%s%s.%09d %7ld %s:%d] ", gpr_log_severity_string(severity),
-          time_buffer, (int)(now.tv_nsec), gettid(), display_file, line);
-  vfprintf(stderr, format, args);
-  fputc('\n', stderr);
-  funlockfile(stderr);
+  fprintf(stderr, "%s%s.%09d %7ld %s:%d] %s\n",
+          gpr_log_severity_string(args->severity), time_buffer,
+          (int)(now.tv_nsec), gettid(), display_file, args->line,
+          args->message);
 }
 
 #endif /* defined(GPR_POSIX_LOG) */
diff --git a/src/core/support/log_win32.c b/src/core/support/log_win32.c
index e6567dca7e..ae5f23a90d 100644
--- a/src/core/support/log_win32.c
+++ b/src/core/support/log_win32.c
@@ -39,12 +39,42 @@
 #include <stdio.h>
 #include <stdarg.h>
 
+void gpr_log(const char *file, int line, gpr_log_severity severity,
+             const char *message) {
+  const char *message = NULL;
+  va_list args;
+  int ret;
+
+  /* Determine the length. */
+  va_start(args, format);
+  ret = _vscprintf(format, args);
+  va_end(args);
+  if (!(0 <= ret && ret < ~(size_t)0)) {
+    message = NULL;
+  } else {
+    /* Allocate a new buffer, with space for the NUL terminator. */
+    strp_buflen = (size_t)ret + 1;
+    message = gpr_malloc(strp_buflen);
+
+    /* Print to the buffer. */
+    va_start(args, format);
+    ret = vsnprintf_s(message, strp_buflen, _TRUNCATE, format, args);
+    va_end(args);
+    if (ret != strp_buflen - 1) {
+      /* This should never happen. */
+      gpr_free(message);
+      message = NULL;
+    }
+  }
+
+  gpr_log_message(file, line, severity, message);
+  gpr_free(message);
+}
+
 /* Simple starter implementation */
-void gpr_vlog(const char *file, int line, gpr_log_severity severity,
-              const char *format, va_list args) {
-  fprintf(stderr, "%s %s:%d: ", gpr_log_severity_string(severity), file, line);
-  vfprintf(stderr, format, args);
-  fputc('\n', stderr);
+void gpr_default_log(gpr_log_func_args *args) {
+  fprintf(stderr, "%s %s:%d: %s\n", gpr_log_severity_string(severity),
+          args->file, args->line, args->message);
 }
 
 #endif