New example on how to import threads to ECL. It's fragile, but hopefully we will add better examples in a near future

examples/threads/import/Makefile

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+#
+# Read the comments in import.c
+#
+
+import.exe: import.c
+	gcc -g `ecl-config --cflags` import.c -o $@ `ecl-config --ldflags`

examples/threads/import/import.c

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+/*
+    import.c -- Execute Lisp code from C-generated threads
+*/
+/*
+    Copyright (c) 2005, Juan Jose Garcia Ripoll.
+
+    ECL is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    See file '../Copyright' for full details.
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+
+/*
+ * GOAL:	To execute lisp code from threads which have not
+ *		been generated by our lisp environment.
+ *
+ * ASSUMES:	ECL has been configured with threads (--enable-threads)
+ *		and installed somewhere on the path.
+ *
+ * COMPILE:	Run "make" from the command line.
+ *
+ *
+ * When this example is compiled and run, it generates a number of
+ * threads, each one executing some interpreted code -- in this case
+ * a bunch of PRINT statements.
+ *
+ * Importing other threads into lisp is possible if these threads have
+ * been intercepted by the garbage collector. The way to do it is to
+ * include the <ecl.h> on the source code that generates the threads,
+ * as we do here. This takes care of replacing calls to phtread_create
+ * or CreateThread (in unix and Windows respectively) with the
+ * GC_pthread_create and GC_CreateThread functions.
+ */
+
+#include <ecl.h>
+
+
+static void *
+thread_entry_point(void *data)
+{
+	cl_object form;
+
+	/*
+	 * This is the entry point of the threads we have created.
+	 * These threads have no valid lisp environment. The following
+	 * routine initializes the lisp and makes it ready for working
+	 * in this thread.
+	 */
+
+	ecl_import_current_thread(Cnil, Cnil);
+
+	/*
+	 * Here we execute some lisp code code.
+	 */
+	cl_eval(form);
+
+	/*
+	 * Finally, when we exit the thread we have to release the
+	 * resources allocated by the lisp environment.
+	 */
+	ecl_release_current_thread();
+
+	return NULL;
+}
+
+
+int main(int narg, char **argv)
+{
+	pthread_t child_thread;
+	int i, code;
+
+	/*
+	 * First of all, we have to initialize the ECL environment.
+	 * This should be done from the main thread.
+	 */
+	cl_boot(narg, argv);
+
+	/*
+	 * Here we spawn 10 threads using the OS functions. The
+	 * current version is for Unix and uses pthread_create.
+	 * Since we have included <gc.h>, pthread_create will be
+	 * replaced with the appropiate routine from the garbage
+	 * collector.
+	 */
+	cl_object sym_print = c_string_to_object("PRINT");
+	for (i = 0; i < 10; i++) {
+		cl_object form = cl_list(2, sym_print, MAKE_FIXNUM(i));
+		code = pthread_create(&child_thread, NULL, thread_entry_point,
+				      (void*)form);
+		if (code) {
+			printf("Unable to create thread\n");
+			exit(1);
+		}
+	}
+
+	/*
+	 * Here we wait for the last thread to finish.
+	 */
+	pthread_join(child_thread, NULL);
+
+	return 0;
+}

examples/threads/import_win32/Makefile

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+import.exe: import.c
+	gcc -g `ecl-config --cflags` import.c -o $@ `ecl-config --ldflags`

examples/threads/import_win32/import.c

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+/*
+    import.c -- Execute Lisp code from C-generated threads
+*/
+/*
+    Copyright (c) 2005, Juan Jose Garcia Ripoll.
+
+    ECL is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    See file '../Copyright' for full details.
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+
+/*
+ * GOAL:	To execute lisp code from threads which have not
+ *		been generated by our lisp environment.
+ *
+ * ASSUMES:	ECL has been configured with threads (--enable-threads)
+ *		and installed somewhere on the path.
+ *
+ * COMPILE:	Run "make" from the command line.
+ *
+ *
+ * When this example is compiled and run, it generates a number of
+ * threads, each one executing some interpreted code -- in this case
+ * a bunch of PRINT statements.
+ *
+ * Importing other threads into lisp is possible if these threads have
+ * been intercepted by the garbage collector. The way to do it is to
+ * include the <ecl.h> on the source code that generates the threads,
+ * as we do here. This takes care of replacing calls to phtread_create
+ * or CreateThread (in unix and Windows respectively) with the
+ * GC_pthread_create and GC_CreateThread functions.
+ */
+
+#include <ecl.h>
+
+#ifdef _MSC_VER
+#define sleep(x) Sleep((x)*1000)
+#endif
+
+static DWORD WINAPI
+thread_entry_point(void *data)
+{
+        cl_object form = (cl_object)data;
+
+        /*
+         * This is the entry point of the threads we have created.
+         * These threads have no valid lisp environment. The following
+         * routine initializes the lisp and makes it ready for working
+         * in this thread.
+         */
+
+        ecl_import_current_thread(Cnil, Cnil);
+
+        /*
+         * Here we execute some lisp code code.
+         */
+        cl_eval(form);
+
+        /*
+         * Finally, when we exit the thread we have to release the
+         * resources allocated by the lisp environment.
+         */
+        ecl_release_current_thread();
+
+        return 1;
+}
+
+
+int main(int narg, char **argv)
+{
+        HANDLE code;
+        DWORD child_thread;
+        int i;
+        cl_object sym_print;
+
+        /*
+         * First of all, we have to initialize the ECL environment.
+         * This should be done from the main thread.
+         */
+        cl_boot(narg, argv);
+
+        /*
+         * Here we spawn 10 threads using the OS functions. The
+         * current version is for Unix and uses pthread_create.
+         * Since we have included <gc.h>, pthread_create will be
+         * replaced with the appropiate routine from the garbage
+         * collector.
+         */
+        sym_print = c_string_to_object("PRINT");
+        for (i = 0; i < 10; i++) {
+                cl_object form = cl_list(2, sym_print, MAKE_FIXNUM(i));
+                code = (HANDLE)CreateThread(NULL, 0, thread_entry_point, form, 0,
+                                            &child_thread);
+                if (code) {
+                        printf("Unable to create thread. Code: %d\n", code);
+                        exit(1);
+                }
+        }
+
+        /*
+         * Here we wait for the last thread to finish.
+         */
+        sleep(10);
+
+        return 0;
+}