[v3,1/4] coroutine: introduce coroutines

From d6798e8d30a5de9381a30638223e8283f0817660 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 13 May 2011 12:20:48 +0200
Subject: [PATCH] allow subclassing of coroutines

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 coroutine-ucontext.c |   45 +++++++++++++++++++++++++++++++++++++--------
 coroutine-win32.c    |   38 +++++++++++++++++++++++++++++++++-----
 qemu-coroutine-int.h |    4 ++--
 qemu-coroutine.c     |   23 ++++++-----------------
 4 files changed, 78 insertions(+), 32 deletions(-)

diff --git a/coroutine-ucontext.c b/coroutine-ucontext.c
index 3a8973e..14a0e81 100644
--- a/coroutine-ucontext.c
+++ b/coroutine-ucontext.c
@@ -27,11 +27,33 @@ 
 #include <ucontext.h>
 #include "qemu-coroutine-int.h"
 
-static Coroutine *new_coroutine;
+struct CoroutineUContext { 
+    Coroutine base;
+
+    jmp_buf env;
+};
+
+typedef struct CoroutineUContext CoroutineUContext;
+
+static CoroutineUContext *new_coroutine;
+
+int qemu_coroutine_switch(Coroutine *from_, Coroutine *to_, int action)
+{
+    CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
+    CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
+    int ret;
+
+    ret = setjmp(from->env);
+    if (ret == 0) {
+        longjmp(to->env, action);
+    } else {
+        return ret;
+    }
+}
 
 static void continuation_trampoline(void)
 {
-    Coroutine *co = new_coroutine;
+    CoroutineUContext *co = new_coroutine;
 
     /* Initialize longjmp environment and switch back to
      * qemu_coroutine_init_env() in the old ucontext. */
@@ -40,16 +62,23 @@  static void continuation_trampoline(void)
     }
 
     while (true) {
-        co->entry(co->data);
-        if (!setjmp(co->env)) {
-            longjmp(co->caller->env, COROUTINE_TERMINATE);
-        }
+        co->base.entry(co->base.data);
+        qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
     }
 }
 
-int qemu_coroutine_init_env(Coroutine *co, size_t stack_size)
+Coroutine *qemu_coroutine_new(size_t stack_size)
+{
+    CoroutineUContext *co;
+    co = qemu_mallocz(sizeof(*co));
+    co->base.stack = qemu_malloc(stack_size);
+    return &co->base;
+}
+
+int qemu_coroutine_init_env(Coroutine *co_, size_t stack_size)
 {
     ucontext_t old_uc, uc;
+    CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
 
     /* Create a new ucontext for switching to the coroutine stack and setting
      * up a longjmp environment. */
@@ -58,7 +87,7 @@  int qemu_coroutine_init_env(Coroutine *co, size_t stack_size)
     }
 
     uc.uc_link = &old_uc;
-    uc.uc_stack.ss_sp = co->stack;
+    uc.uc_stack.ss_sp = co->base.stack;
     uc.uc_stack.ss_size = stack_size;
     uc.uc_stack.ss_flags = 0;
 
diff --git a/coroutine-win32.c b/coroutine-win32.c
index 99141dd..5301975 100644
--- a/coroutine-win32.c
+++ b/coroutine-win32.c
@@ -24,20 +24,48 @@ 
 
 #include "qemu-coroutine-int.h"
 
-static void __attribute__((used)) trampoline(Coroutine *co)
+struct CoroutineWin32 { 
+    Coroutine base;
+
+    jmp_buf env;
+};
+
+typedef struct CoroutineWin32 CoroutineWin32;
+
+int qemu_coroutine_switch(Coroutine *from_, Coroutine *to_, int action)
+{
+    CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
+    CoroutineWin32 *to = DO_UPCAST(CoroutineWin32, base, to_);
+    int ret;
+
+    ret = setjmp(from->env);
+    if (ret == 0) {
+        longjmp(to->env, action);
+    } else {
+        return ret;
+    }
+}
+
+static void __attribute__((used)) trampoline(CoroutineWin32 *co)
 {
     if (!setjmp(co->env)) {
         return;
     }
 
     while (true) {
-        co->entry(co->data);
-        if (!setjmp(co->env)) {
-            longjmp(co->caller->env, COROUTINE_TERMINATE);
-        }
+        co->base.entry(co->base.data);
+        qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
     }
 }
 
+Coroutine *qemu_coroutine_new(size_t stack_size)
+{
+    CoroutineWin32 *co;
+    co = qemu_mallocz(sizeof(*co));
+    co->base.stack = qemu_malloc(stack_size);
+    return &co->base;
+}
+
 int qemu_coroutine_init_env(Coroutine *co, size_t stack_size)
 {
 #ifdef __i386__
diff --git a/qemu-coroutine-int.h b/qemu-coroutine-int.h
index 71c6ee9..04eb41a 100644
--- a/qemu-coroutine-int.h
+++ b/qemu-coroutine-int.h
@@ -44,10 +44,10 @@  struct Coroutine {
     /* Used to pass arguments/return values for coroutines */
     void *data;
     CoroutineEntry *entry;
-
-    jmp_buf env;
 };
 
 int qemu_coroutine_init_env(Coroutine *co, size_t stack_size);
+int qemu_coroutine_switch(Coroutine *from_, Coroutine *to_, int action);
+Coroutine *qemu_coroutine_new(size_t stack_size);
 
 #endif
diff --git a/qemu-coroutine.c b/qemu-coroutine.c
index a80468b..02c345d 100644
--- a/qemu-coroutine.c
+++ b/qemu-coroutine.c
@@ -34,24 +34,15 @@  static void coroutine_terminate(Coroutine *co)
     qemu_free(co);
 }
 
-static Coroutine *coroutine_new(void)
-{
-    const size_t stack_size = 4 << 20;
-    Coroutine *co;
-
-    co = qemu_mallocz(sizeof(*co));
-    co->stack = qemu_malloc(stack_size);
-    qemu_coroutine_init_env(co, stack_size);
-    return co;
-}
-
 Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
 {
+    const size_t stack_size = 4 << 20;
     Coroutine *co;
 
-    co = coroutine_new();
+    co = qemu_coroutine_new(stack_size);
     co->entry = entry;
 
+    qemu_coroutine_init_env(co, stack_size);
     return co;
 }
 
@@ -76,7 +67,8 @@  static void *coroutine_swap(Coroutine *from, Coroutine *to, void *opaque)
 
     to->data = opaque;
 
-    ret = setjmp(from->env);
+    current = to;
+    ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);
     switch (ret) {
     case COROUTINE_YIELD:
         return from->data;
@@ -86,10 +78,7 @@  static void *coroutine_swap(Coroutine *from, Coroutine *to, void *opaque)
         coroutine_terminate(to);
         return to_data;
     default:
-        /* Switch to called coroutine */
-        current = to;
-        longjmp(to->env, COROUTINE_YIELD);
-        return NULL;
+        abort();
     }
 }
 
-- 
1.7.4.4