a palliative for race condition problem

src/Makefile

@@ -9,10 +9,11 @@ CXX=g++
 CC=gcc
 #OPTFLAGS=-g -O0
 OPTFLAGS=-O3 -DBOOST_UBLAS_NDEBUG -DNDEBUG
+MYFLAGS=-DNO_THREADS
 BOOST_CFLAGS=-I/usr/local/include/boost-1_35
 TAGLIB_CFLAGS=`taglib-config --cflags`
 TAGLIB_LIBS=`taglib-config --libs`
-CXXFLAGS=-Wall $(BOOST_CFLAGS) $(TAGLIB_CFLAGS) -fPIC $(OPTFLAGS)
+CXXFLAGS=-Wall $(BOOST_CFLAGS) $(TAGLIB_CFLAGS) -fPIC $(OPTFLAGS) $(MYFLAGS)
 CFLAGS=-Wall -fPIC $(OPTFLAGS)
 LDFLAGS=$(TAGLIB_LIBS) -lz -lpthread $(OPTFLAGS)
 LIBNAME=libcodegen.so

src/main.cxx

@@ -167,6 +167,11 @@ void *threaded_codegen_file(void *parm) {
     return NULL;
 }
 
+#ifdef NO_THREADS
+// no difference.
+#define nothread_codegen_file threaded_codegen_file
+#endif
+
 void print_json_to_screen(char* output, int count, int done) {
     // Print a json block depending on how many there are and where we are.
     if(done==1 && count>1) {
@@ -186,23 +191,13 @@ char *make_json_string(codegen_response_t* response) {
         return response->error;
     }
 
-    // Get the ID3 tag information.
-    auto_ptr<Metadata> pMetadata(new Metadata(response->filename));
-
     // preamble + codelen
     char* output = (char*) malloc(sizeof(char)*(16384 + strlen(response->codegen->getCodeString().c_str()) ));
 
-    sprintf(output,"{\"metadata\":{\"artist\":\"%s\", \"release\":\"%s\", \"title\":\"%s\", \"genre\":\"%s\", \"bitrate\":%d,"
-                    "\"sample_rate\":%d, \"duration\":%d, \"filename\":\"%s\", \"samples_decoded\":%d, \"given_duration\":%d,"
+    sprintf(output,"{\"metadata\":{\"artist\":\"\", \"release\":\"\", \"title\":\"\", \"genre\":\"\", \"bitrate\":0,"
+                    "\"sample_rate\":0, \"duration\":0, \"filename\":\"%s\", \"samples_decoded\":%d, \"given_duration\":%d,"
                     " \"start_offset\":%d, \"version\":%2.2f, \"codegen_time\":%2.6f, \"decode_time\":%2.6f}, \"code_count\":%d,"
                     " \"code\":\"%s\", \"tag\":%d}",
-        escape(pMetadata->Artist()).c_str(),
-        escape(pMetadata->Album()).c_str(),
-        escape(pMetadata->Title()).c_str(),
-        escape(pMetadata->Genre()).c_str(),
-        pMetadata->Bitrate(),
-        pMetadata->SampleRate(),
-        pMetadata->Seconds(),
         escape(response->filename).c_str(),
         response->numSamples,
         response->duration,
@@ -272,10 +267,12 @@ int main(int argc, char** argv) {
         if (num_threads < 2) num_threads = 2;
         if (num_threads > count) num_threads = count;
 
+        thread_parm_t **parm = (thread_parm_t**)malloc(sizeof(thread_parm_t*)*num_threads);
+#ifndef NO_THREADS
         // Setup threading
         pthread_t *t = (pthread_t*)malloc(sizeof(pthread_t)*num_threads);
-        thread_parm_t **parm = (thread_parm_t**)malloc(sizeof(thread_parm_t*)*num_threads);
         pthread_attr_t *attr = (pthread_attr_t*)malloc(sizeof(pthread_attr_t)*num_threads);
+#endif
 
         // Kick off the first N threads
         int still_left = count-1-already;
@@ -287,19 +284,27 @@ int main(int argc, char** argv) {
             parm[i]->duration = duration;
             parm[i]->done = 0;
             still_left--;
+#ifndef NO_THREADS
             pthread_attr_init(&attr[i]);
             pthread_attr_setdetachstate(&attr[i], PTHREAD_CREATE_DETACHED);
             // Kick off the thread
             if (pthread_create(&t[i], &attr[i], threaded_codegen_file, (void*)parm[i]))
                 throw std::runtime_error("Problem creating thread\n");
+#else
+	    // run sequentially, one by one
+	    nothread_codegen_file((void*)parm[i]);
+#endif
         }
 
         int done = 0;
         // Now wait for the threads to come back, and also kick off new ones
         while(done<count) {
             // Check which threads are done
+	    //                              -- this is an inefficient polling. Please consider using
+	    //                                 mutex and condvar instead of this "lockfree" algorithm
             for(int i=0;i<num_threads;i++) {
-                if (parm[i]->done) {
+                if (parm[i]->done) { // There is a race condition here in the threaded version.
+				     // We get a coredump file every hour.
                     parm[i]->done = 0;
                     done++;
                     codegen_response_t *response = (codegen_response_t*)parm[i]->response;
@@ -315,10 +320,13 @@ int main(int argc, char** argv) {
                         parm[i]->tag = still_left;
                         parm[i]->filename = (char*)files[still_left].c_str();
                         still_left--;
+#ifndef NO_THREADS
                         int err= pthread_create(&t[i], &attr[i], threaded_codegen_file, (void*)parm[i]);
                         if(err)
                             throw std::runtime_error("Problem creating thread\n");
-
+#else
+			nothread_codegen_file((void*)parm[i]);
+#endif
                     }
                 }
             }
@@ -328,9 +336,11 @@ int main(int argc, char** argv) {
         for(int i=0;i<num_threads;i++) {
             free(parm[i]);
         }
+#ifndef NO_THREADS
         free(t);
-        free(parm);
         free(attr);
+#endif
+        free(parm);
         return 0;
 
 #endif // _WIN32