Create example01

README.md

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+# What this repo is
+
+This repo has some examples using multi-threaded-programming because someone
+asked about how it works.

example01_singleThread_c_impl/.gitignore

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+build*/
+compile_commands.json
+.cache/

example01_singleThread_c_impl/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.9)
+project(Example01_SingleThread_C_IMPL)
+
+set(Example01_SOURCES
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/main.c")
+
+set(CMAKE_C_FLAGS "-Wall -Wextra -Wpedantic")
+set(CMAKE_C_FLAGS_DEBUG "-O0 -g")
+set(CMAKE_C_FLAGS_RELEASE "-O3 -DNDEBUG")
+
+if(NOT CMAKE_BUILD_TYPE OR "${CMAKE_BUILD_TYPE}" MATCHES ^$)
+    set(CMAKE_BUILD_TYPE "Debug")
+    message("CMAKE_BUILD_TYPE is set to Debug by default")
+endif()
+
+add_executable(Example01
+    ${Example01_SOURCES})
+
+target_link_libraries(Example01 PUBLIC pthread)

example01_singleThread_c_impl/src/main.c

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+#include <stdio.h>
+#include <threads.h>
+#include <string.h>
+
+typedef struct ThreadData {
+    mtx_t mutex;
+    int lock_before_printing;
+} ThreadData;
+
+int functionCalledByThread(void *user_data) {
+    ThreadData *data = (ThreadData*)user_data;
+
+    if(data->lock_before_printing != 0) {
+        // lock before printing
+        mtx_lock(&data->mutex);
+    }
+    puts("Hello from spawned thread");
+    if(data->lock_before_printing != 0) {
+        // unlock after printing
+        mtx_unlock(&data->mutex);
+    }
+
+    return 0;
+}
+
+int main(int argc, char **argv) {
+    // create the ThreadData that is shared with the thread
+    ThreadData td;
+    mtx_init(&td.mutex, mtx_plain);
+    td.lock_before_printing = 1;
+
+    // check args
+    --argc; ++argv;
+    while(argc > 0) {
+        if(strcmp("-n", argv[0]) == 0 || strcmp("--no-lock", argv[0]) == 0) {
+            td.lock_before_printing = 0;
+            puts("Disabling use of mutex before printing");
+        }
+        --argc; ++argv;
+    }
+
+    // create the thread
+    thrd_t thread_handle;
+    thrd_create(&thread_handle, functionCalledByThread, &td);
+
+    if(td.lock_before_printing != 0) {
+        // lock before printing
+        mtx_lock(&td.mutex);
+    }
+    puts("Hello from main thread");
+    if(td.lock_before_printing != 0) {
+        // unlock after printing
+        mtx_unlock(&td.mutex);
+    }
+
+    thrd_join(thread_handle, NULL);
+
+    // cleanup
+    mtx_destroy(&td.mutex);
+    return 0;
+}