From 9259ed8f267337f54b29c87f445b004e3ca52de0 Mon Sep 17 00:00:00 2001
From: Stefan Weil <sw@weilnetz.de>
Date: Wed, 10 Jul 2019 20:59:07 +0200
Subject: [PATCH] Optimize tprintf implementation

It no longer uses a local buffer, so it needs less memory
and no mutex.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 src/ccutil/ccutil.cpp  |  1 -
 src/ccutil/ccutil.h    |  1 -
 src/ccutil/tprintf.cpp | 48 +++++++++++++++++++++---------------------
 3 files changed, 24 insertions(+), 26 deletions(-)

diff --git a/src/ccutil/ccutil.cpp b/src/ccutil/ccutil.cpp
index 79ea6623..bf07a2a4 100644
--- a/src/ccutil/ccutil.cpp
+++ b/src/ccutil/ccutil.cpp
@@ -52,5 +52,4 @@ void CCUtilMutex::Unlock() {
 #endif
 }
 
-CCUtilMutex tprintfMutex;  // should remain global
 } // namespace tesseract
diff --git a/src/ccutil/ccutil.h b/src/ccutil/ccutil.h
index 71e89c60..3dd63711 100644
--- a/src/ccutil/ccutil.h
+++ b/src/ccutil/ccutil.h
@@ -87,7 +87,6 @@ class CCUtil {
              "Use ambigs for deciding whether to adapt to a character");
 };
 
-extern CCUtilMutex tprintfMutex;  // should remain global
 }  // namespace tesseract
 
 #endif  // TESSERACT_CCUTIL_CCUTIL_H_
diff --git a/src/ccutil/tprintf.cpp b/src/ccutil/tprintf.cpp
index 44cd29c9..89bea92e 100644
--- a/src/ccutil/tprintf.cpp
+++ b/src/ccutil/tprintf.cpp
@@ -23,7 +23,6 @@
 
 #include <cstdio>
 #include <cstdarg>
-#include "ccutil.h"
 #include "params.h"
 #include "strngs.h"
 #include "tprintf.h"
@@ -35,34 +34,35 @@ static STRING_VAR(debug_file, "", "File to send tprintf output to");
 // Trace printf
 DLLSYM void tprintf(const char *format, ...)
 {
-  tesseract::tprintfMutex.Lock();
-  va_list args;                  // variable args
   const char* debug_file_name = debug_file.string();
   static FILE *debugfp = nullptr;   // debug file
-                                 // debug window
-  int32_t offset = 0;              // into message
-  char msg[MAX_MSG_LEN + 1];
 
-  va_start(args, format);  // variable list
-  // Format into msg
-  #ifdef _WIN32
-  offset += _vsnprintf(msg + offset, MAX_MSG_LEN - offset, format, args);
-  if (debug_file_name && strcmp(debug_file_name, "/dev/null") == 0)
-    debug_file.set_value("nul");
-  #else
-  offset += vsnprintf(msg + offset, MAX_MSG_LEN - offset, format, args);
-  #endif
-  va_end(args);
+  if (debug_file_name == nullptr) {
+    // This should not happen.
+    return;
+  }
 
-  if (debugfp == nullptr && debug_file_name && strlen(debug_file_name) > 0) {
-    debugfp = fopen(debug_file.string(), "wb");
-  } else if (debugfp != nullptr && debug_file_name && strlen(debug_file_name) == 0) {
+#ifdef _WIN32
+  // Replace /dev/null by nul for Windows.
+  if (strcmp(debug_file_name, "/dev/null") == 0) {
+    debug_file_name = "nul";
+    debug_file.set_value(debug_file_name);
+  }
+#endif
+
+  if (debugfp == nullptr && debug_file_name[0] != '\0') {
+    debugfp = fopen(debug_file_name, "wb");
+  } else if (debugfp != nullptr && debug_file_name[0] == '\0') {
     fclose(debugfp);
     debugfp = nullptr;
   }
-  if (debugfp != nullptr)
-    fprintf(debugfp, "%s", msg);
-  else
-    fprintf(stderr, "%s", msg);
-  tesseract::tprintfMutex.Unlock();
+
+  va_list args;            // variable args
+  va_start(args, format);  // variable list
+  if (debugfp != nullptr) {
+    vfprintf(debugfp, format, args);
+  } else {
+    vfprintf(stderr, format, args);
+  }
+  va_end(args);
 }