libtf: initial commit

libtf is to be user-space cooperative threading library similar
to State Threads (http://state-threads.sourceforge.net/), but
with additional support for multiple cores, using better
algorithms and taking advantage of new Linux kernel syscalls
such as eventfd, signalfd and epoll (edge-triggered mode).

Initial implementation has setjmp based user-space context
switching and trivial testcase. Works on Linux/x86.

TFbuild uses ideas from different build systems, namely Kbuild,
but it's inner workings are quite different. All build files are
included (using macro trickery) instead of recursive making. Thus
the build dependency graph is complete and should yield good make
performance. Also parallel stuff should work.

3 files changed, 245 insertions, 0 deletions

diff --git a/src/TFbuild b/src/TFbuild
new file mode 100644
index 0000000..211b734
--- /dev/null
+++ b/src/TFbuild
@@ -0,0 +1,5 @@
+libs-y			+= libtf
+
+libtf-objs-y		+= fiber.o dheap.o
+
+CFLAGS_dheap.c		+= -funroll-all-loops
diff --git a/src/fiber.c b/src/fiber.c
new file mode 100644
index 0000000..0db2984
--- /dev/null
+++ b/src/fiber.c
@@ -0,0 +1,131 @@
+/* fiber.c - fiber management and scheduling
+ *
+ * Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or later as
+ * published by the Free Software Foundation.
+ *
+ * See http://www.gnu.org/ for details.
+ */
+#include <errno.h>
+#include <libtf/tf.h>
+#include TF_UCTX_H
+
+struct tf_scheduler {
+	struct tf_list_head	run_q;
+	struct tf_list_head	sleep_q;
+
+	struct tf_fiber *	active_fiber;
+	int			num_fibers;
+};
+
+/* FIXME: should be in thread local storage */
+static struct tf_scheduler *__scheduler;
+
+void *tf_fiber_create(tf_fiber_proc fiber_main, int private_size)
+{
+	struct tf_scheduler *sched = __scheduler;
+	struct tf_fiber *fiber;
+
+	fiber = tf_uctx_create(fiber_main, private_size);
+
+	/* The initial references for caller and scheduler */
+	*fiber = (struct tf_fiber) {
+		.ref_count = 2,
+		.queue_node = TF_LIST_INITIALIZER(fiber->queue_node),
+	};
+
+	tf_list_add_tail(&fiber->queue_node, &sched->run_q);
+	sched->num_fibers++;
+
+	return fiber->data;
+}
+
+void __tf_fiber_destroy(struct tf_fiber *fiber)
+{
+	tf_uctx_destroy(fiber);
+}
+
+void *tf_fiber_get(void *data)
+{
+	struct tf_fiber *fiber = container_of(data, struct tf_fiber, data);
+	tf_atomic_inc(fiber->ref_count);
+	return data;
+}
+
+void tf_fiber_put(void *data)
+{
+	struct tf_fiber *fiber = container_of(data, struct tf_fiber, data);
+	if (tf_atomic_dec(fiber->ref_count) == 0)
+		__tf_fiber_destroy(fiber);
+}
+
+static void run_fiber(void)
+{
+	struct tf_scheduler *sched = __scheduler;
+	struct tf_fiber *schedf = container_of((void*) __scheduler, struct tf_fiber, data);
+	struct tf_fiber *f;
+
+	if (tf_list_empty(&sched->run_q))
+		return;
+
+	f = tf_list_first(&sched->run_q, struct tf_fiber, queue_node);
+	tf_list_del(&f->queue_node);
+
+	sched->active_fiber = f;
+	switch (tf_uctx_transfer(schedf, f, 1)) {
+	case EFAULT: /* Fiber is dead */
+		tf_fiber_put(f->data);
+		sched->num_fibers--;
+		break;
+	case EAGAIN: /* Yielded, reshedule */
+		tf_list_add_tail(&f->queue_node, &sched->run_q);
+		break;
+	case EIO: /* Blocked, in sleep */
+		tf_list_add_tail(&f->queue_node, &sched->sleep_q);
+		break;
+	default:
+		TF_BUG_ON("bad scheduler call from fiber");
+	}
+}
+
+int tf_main(tf_fiber_proc main_fiber)
+{
+	struct tf_uctx *ctx = alloca(sizeof(struct tf_uctx) + sizeof(struct tf_scheduler));
+	struct tf_scheduler *sched = (struct tf_scheduler*) ctx->fiber.data;
+	int stack_guard = STACK_GUARD;
+
+	ctx->stack_guard = &stack_guard;
+	*sched = (struct tf_scheduler){
+		.run_q = TF_LIST_HEAD_INITIALIZER(sched->run_q),
+		.sleep_q = TF_LIST_HEAD_INITIALIZER(sched->sleep_q),
+	};
+	__scheduler = sched;
+	tf_fiber_put(tf_fiber_create(main_fiber, 0));
+	do {
+		run_fiber();
+	} while (likely(sched->num_fibers));
+	__scheduler = NULL;
+
+	return 0;
+}
+
+int tf_schedule(int err)
+{
+	struct tf_scheduler *sched = __scheduler;
+	struct tf_fiber *schedf = container_of((void*) __scheduler, struct tf_fiber, data);
+	struct tf_fiber *f = sched->active_fiber;
+	int r;
+
+	r = tf_uctx_transfer(f, schedf, err);
+	if (r == 1)
+		return 0;
+
+	return r;
+}
+
+void tf_kill(void *fiber)
+{
+}
diff --git a/src/uctx-setjmp.h b/src/uctx-setjmp.h
new file mode 100644
index 0000000..33e187e
--- /dev/null
+++ b/src/uctx-setjmp.h
@@ -0,0 +1,109 @@
+/* uctx-setjmp.h - setjmp based user-space context switching
+ *
+ * Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or later as
+ * published by the Free Software Foundation.
+ *
+ * See http://www.gnu.org/ for details.
+ */
+
+#include <libtf/fiber.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <setjmp.h>
+#ifdef VALGRIND
+#include <valgrind/valgrind.h>
+#endif
+
+#define STACK_GUARD		0xbad57ac4
+
+struct tf_uctx {
+	int *stack_guard;
+	void *alloc;
+	jmp_buf jmpbuf;
+#ifdef VALGRIND
+	unsigned int stack_id;
+#endif
+	struct tf_fiber fiber;
+};
+
+#define set_stack(ptr) ({ __asm__("movl %0, %%esp" : : "r"(ptr)); })
+#define get_stack() ({ void *ptr; __asm__("movl %%esp, %0" : "=r"(ptr)); ptr; })
+
+attribute_never_inline
+static void *tf_uctx_start(tf_fiber_proc fiber_main, size_t private_size)
+{
+	struct tf_uctx *uctx;
+
+	uctx = alloca(private_size);
+	if (setjmp(uctx->jmpbuf) != 0) {
+		fiber_main(uctx->fiber.data);
+		tf_exit();
+	}
+	return uctx;
+}
+
+static inline
+struct tf_fiber *tf_uctx_create(tf_fiber_proc fiber_main, int private_size)
+{
+	size_t size = TF_STACK_SIZE;
+	struct tf_uctx *uctx;
+	void *stack, *old_stack, *stack_head, *stack_tail;
+#ifdef VALGRIND
+	int stack_id;
+#endif
+
+	stack = malloc(size);
+	if (stack == NULL)
+		return NULL;
+#ifdef VALGRIND
+	stack_id = VALGRIND_STACK_REGISTER(stack, size);
+#endif
+
+	/* Assumes stack grows up */
+	stack_head = stack + size - 8;
+	stack_tail = stack;
+
+	old_stack = get_stack();
+	set_stack(stack_head);
+	uctx = tf_uctx_start(fiber_main, private_size + sizeof(struct tf_uctx));
+	set_stack(old_stack);
+
+#ifdef VALGRIND
+	uctx->stack_id = stack_id;
+#endif
+	uctx->alloc = stack;
+	uctx->stack_guard = stack_tail;
+	*uctx->stack_guard = STACK_GUARD;
+
+	return &uctx->fiber;
+}
+
+static inline
+void tf_uctx_destroy(struct tf_fiber *fiber)
+{
+	struct tf_uctx *uctx = container_of(fiber, struct tf_uctx, fiber);
+#ifdef VALGRIND
+	VALGRIND_STACK_DEREGISTER(uctx->stack_id);
+#endif
+	free(uctx->alloc);
+}
+
+static inline
+int tf_uctx_transfer(struct tf_fiber *from, struct tf_fiber *to, int value)
+{
+	struct tf_uctx *ufrom = container_of(from, struct tf_uctx, fiber);
+	struct tf_uctx *uto   = container_of(to,   struct tf_uctx, fiber);
+	int r;
+
+	TF_BUG_ON(unlikely(*ufrom->stack_guard != STACK_GUARD));
+
+	r = setjmp(ufrom->jmpbuf);
+	if (r == 0)
+		longjmp(uto->jmpbuf, value);
+	return r;
+}