Imported Upstream version 16.04

[deb_dpdk.git] / examples / performance-thread / pthread_shim / pthread_shim.h

diff --git a/examples/performance-thread/pthread_shim/pthread_shim.h b/examples/performance-thread/pthread_shim/pthread_shim.h
new file mode 100644 (file)
index 0000000..78bbb5a
--- /dev/null
+++ b/examples/performance-thread/pthread_shim/pthread_shim.h
@@ -0,0 +1,113 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2015 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _PTHREAD_SHIM_H_
+#define _PTHREAD_SHIM_H_
+#include <pthread.h>
+
+/*
+ * This pthread shim is an example that demonstrates how legacy code
+ * that makes use of POSIX pthread services can make use of lthreads
+ * with reduced porting effort.
+ *
+ * N.B. The example is not a complete implementation, only a subset of
+ * pthread APIs sufficient to demonstrate the principle of operation
+ * are implemented.
+ *
+ * In general pthread attribute objects do not have equivalent functions
+ * in lthreads, and are ignored.
+ *
+ * There is one exception and that is the use of attr to specify a
+ * core affinity in calls to pthread_create.
+ *
+ * The shim operates as follows:-
+ *
+ * On initialisation a constructor function uses dlsym to obtain and
+ * save the loaded address of the full set of pthread APIs that will
+ * be overridden.
+ *
+ * For each function there is a stub provided that will invoke either
+ * the genuine pthread library function saved saved by the constructor,
+ * or else the corresponding equivalent lthread function.
+ *
+ * The stub functions are implemented in pthread_shim.c
+ *
+ * The stub will take care of adapting parameters, and any police
+ * any constraints where lthread functionality differs.
+ *
+ * The initial thread must always be a pure lthread.
+ *
+ * The decision whether to invoke the real library function or the lthread
+ * function is controlled by a per pthread flag that can be switched
+ * on of off by the pthread_override_set() API described below. Typcially
+ * this should be done as the first action of the initial lthread.
+ *
+ * N.B In general it would be poor practice to revert to invoke a real
+ * pthread function when running as an lthread, since these may block and
+ * effectively stall the lthread scheduler.
+ *
+ */
+
+
+/*
+ * An exiting lthread must not terminate the pthread it is running in
+ * since this would mean terminating the lthread scheduler.
+ * We override pthread_exit() with a macro because it is typically declared with
+ * __attribute__((noreturn))
+ */
+void pthread_exit_override(void *v);
+
+#define pthread_exit(v) do { \
+       pthread_exit_override((v));     \
+       return NULL;    \
+} while (0)
+
+/*
+ * Enable/Disable pthread override
+ * state
+ * 0 disable
+ * 1 enable
+ */
+void pthread_override_set(int state);
+
+
+/*
+ * Return pthread override state
+ * return
+ * 0 disable
+ * 1 enable
+ */
+int pthread_override_get(void);
+
+
+#endif /* _PTHREAD_SHIM_H_ */