Make os/execute cooperate with ev module.

os/execute, os/proc-wait do not block (currently posix only).
This uses the self-pipe trick to turn signals into a pollable entity.

src/core/ev.c

@@ -48,6 +48,7 @@
 #include <netinet/tcp.h>
 #include <netdb.h>
 #include <sys/socket.h>
+#include <sys/wait.h>
 #ifdef JANET_EV_EPOLL
 #include <sys/epoll.h>
 #include <sys/timerfd.h>
@@ -147,6 +148,7 @@ JANET_THREAD_LOCAL JanetRNG janet_vm_ev_rng;
 JANET_THREAD_LOCAL JanetListenerState **janet_vm_listeners = NULL;
 JANET_THREAD_LOCAL size_t janet_vm_listener_count = 0;
 JANET_THREAD_LOCAL size_t janet_vm_listener_cap = 0;
+JANET_THREAD_LOCAL size_t janet_vm_extra_listeners = 0;
 
 /* Get current timestamp (millisecond precision) */
 static JanetTimestamp ts_now(void);
@@ -491,6 +493,14 @@ void janet_addtimeout(double sec) {
     add_timeout(to);
 }
 
+void janet_ev_inc_refcount(void) {
+    janet_vm_extra_listeners++;
+}
+
+void janet_ev_dec_refcount(void) {
+    janet_vm_extra_listeners--;
+}
+
 /* Channels */
 
 typedef struct {
@@ -774,14 +784,16 @@ void janet_loop1(void) {
             }
         }
     }
+
     /* Run scheduled fibers */
     while (janet_vm_spawn.head != janet_vm_spawn.tail) {
         JanetTask task = {NULL, janet_wrap_nil(), JANET_SIGNAL_OK};
         janet_q_pop(&janet_vm_spawn, &task, sizeof(task));
         run_one(task.fiber, task.value, task.sig);
     }
+
     /* Poll for events */
-    if (janet_vm_listener_count || janet_vm_tq_count) {
+    if (janet_vm_listener_count || janet_vm_tq_count || janet_vm_extra_listeners) {
         JanetTimeout to;
         memset(&to, 0, sizeof(to));
         int has_timeout;
@@ -790,18 +802,67 @@ void janet_loop1(void) {
             pop_timeout(0);
         }
         /* Run polling implementation only if pending timeouts or pending events */
-        if (janet_vm_tq_count || janet_vm_listener_count) {
+        if (janet_vm_tq_count || janet_vm_listener_count || janet_vm_extra_listeners) {
             janet_loop1_impl(has_timeout, to.when);
         }
     }
 }
 
 void janet_loop(void) {
-    while (janet_vm_listener_count || (janet_vm_spawn.head != janet_vm_spawn.tail) || janet_vm_tq_count) {
+    while (janet_vm_listener_count || (janet_vm_spawn.head != janet_vm_spawn.tail) || janet_vm_tq_count || janet_vm_extra_listeners) {
         janet_loop1();
     }
 }
 
+/*
+ * Signal handling code.
+ */
+
+#ifdef JANET_WINDOWS
+
+#else
+
+JANET_THREAD_LOCAL int janet_vm_selfpipe[2];
+
+static void janet_ev_handle_signals(void) {
+    int sig = 0;
+    while (read(janet_vm_selfpipe[0], &sig, sizeof(sig)) > 0) {
+        switch (sig) {
+            default:
+                break;
+            case SIGCHLD:
+                {
+                    int status = 0;
+                    pid_t pid = waitpid(-1, &status, WNOHANG | WUNTRACED);
+                    /* invalid pid on failure will do no harm */
+                    janet_schedule_pid(pid, status);
+                }
+                break;
+        }
+    }
+}
+
+static void janet_sig_handler(int sig) {
+    int result = write(janet_vm_selfpipe[1], &sig, sizeof(sig));
+    if (result) {
+        /* Failed to handle signal. */
+        ;
+    }
+    signal(sig, janet_sig_handler);
+}
+
+static void janet_ev_setup_signals(void) {
+    if (-1 == pipe(janet_vm_selfpipe)) goto error;
+    if (fcntl(janet_vm_selfpipe[0], F_SETFL, O_NONBLOCK)) goto error;
+    if (fcntl(janet_vm_selfpipe[1], F_SETFL, O_NONBLOCK)) goto error;
+    signal(SIGCHLD, janet_sig_handler);
+    return;
+error:
+    JANET_EXIT("failed to initialize self pipe in event loop");
+}
+
+#endif
+
 #ifdef JANET_WINDOWS
 
 JANET_THREAD_LOCAL HANDLE janet_vm_iocp = NULL;
@@ -969,8 +1030,14 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
 
     /* Step state machines */
     for (int i = 0; i < ready; i++) {
-        JanetStream *stream = events[i].data.ptr;
-        if (NULL != stream) { /* If NULL, is a timeout */
+        void *p = events[i].data.ptr;
+        if (&janet_vm_timerfd == p) {
+            /* Timer expired, ignore */;
+        } else if (janet_vm_selfpipe == p) {
+            /* Signal */
+            janet_ev_handle_signals();
+        } else {
+            JanetStream *stream = p;
             int mask = events[i].events;
             JanetListenerState *state = stream->state;
             state->event = events + i;
@@ -1001,14 +1068,18 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
 
 void janet_ev_init(void) {
     janet_ev_init_common();
+    janet_ev_setup_signals();
     janet_vm_epoll = epoll_create1(EPOLL_CLOEXEC);
     janet_vm_timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK);
     janet_vm_timer_enabled = 0;
     if (janet_vm_epoll == -1 || janet_vm_timerfd == -1) goto error;
     struct epoll_event ev;
     ev.events = EPOLLIN | EPOLLET;
-    ev.data.ptr = NULL;
+    ev.data.ptr = &janet_vm_timerfd;
     if (-1 == epoll_ctl(janet_vm_epoll, EPOLL_CTL_ADD, janet_vm_timerfd, &ev)) goto error;
+    ev.events = EPOLLIN | EPOLLET;
+    ev.data.ptr = janet_vm_selfpipe;
+    if (-1 == epoll_ctl(janet_vm_epoll, EPOLL_CTL_ADD, janet_vm_selfpipe[0], &ev)) goto error;
     return;
 error:
     JANET_EXIT("failed to initialize event loop");
@@ -1054,7 +1125,7 @@ JanetListenerState *janet_listen(JanetStream *stream, JanetListener behavior, in
     JanetListenerState *state = janet_listen_impl(stream, behavior, mask, size, user);
     size_t newsize = janet_vm_listener_cap;
     if (newsize > oldsize) {
-        janet_vm_fds = realloc(janet_vm_fds, newsize * sizeof(struct pollfd));
+        janet_vm_fds = realloc(janet_vm_fds, (newsize + 1) * sizeof(struct pollfd));
         if (NULL == janet_vm_fds) {
             JANET_OUT_OF_MEMORY;
         }
@@ -1063,12 +1134,12 @@ JanetListenerState *janet_listen(JanetStream *stream, JanetListener behavior, in
     ev.fd = stream->handle;
     ev.events = make_poll_events(state->stream->_mask);
     ev.revents = 0;
-    janet_vm_fds[state->_index] = ev;
+    janet_vm_fds[state->_index + 1] = ev;
     return state;
 }
 
 static void janet_unlisten(JanetListenerState *state) {
-    janet_vm_fds[state->_index] = janet_vm_fds[janet_vm_listener_count - 1];
+    janet_vm_fds[state->_index + 1] = janet_vm_fds[janet_vm_listener_count];
     janet_unlisten_impl(state);
 }
 
@@ -1081,19 +1152,25 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
             JanetTimestamp now = ts_now();
             to = now > timeout ? 0 : (int)(timeout - now);
         }
-        ready = poll(janet_vm_fds, janet_vm_listener_count, to);
+        ready = poll(janet_vm_fds, janet_vm_listener_count + 1, to);
     } while (ready == -1 && errno == EINTR);
     if (ready == -1) {
         JANET_EXIT("failed to poll events");
     }
 
+    /* Check selfpipe */
+    if (janet_vm_fds[0].revents & POLLIN) {
+        janet_vm_fds[0].revents = 0;
+        janet_ev_handle_signals();
+    }
+
     /* Step state machines */
     for (size_t i = 0; i < janet_vm_listener_count; i++) {
-        struct pollfd *pfd = janet_vm_fds + i;
+        struct pollfd *pfd = janet_vm_fds + i + 1;
         /* Skip fds where nothing interesting happened */
         JanetListenerState *state = janet_vm_listeners[i];
         /* Normal event */
-        int mask = janet_vm_fds[i].revents;
+        int mask = pfd->revents;
         JanetAsyncStatus status1 = JANET_ASYNC_STATUS_NOT_DONE;
         JanetAsyncStatus status2 = JANET_ASYNC_STATUS_NOT_DONE;
         JanetAsyncStatus status3 = JANET_ASYNC_STATUS_NOT_DONE;
@@ -1118,12 +1195,22 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp timeout) {
 void janet_ev_init(void) {
     janet_ev_init_common();
     janet_vm_fds = NULL;
+    janet_ev_setup_signals();
+    janet_vm_fds = malloc(sizeof(struct pollfd));
+    if (NULL == janet_vm_fds) {
+        JANET_OUT_OF_MEMORY;
+    }
+    janet_vm_fds[0].fd = janet_vm_selfpipe[0];
+    janet_vm_fds[0].events = POLLIN;
+    janet_vm_fds[0].revents = 0;
     return;
 }
 
 void janet_ev_deinit(void) {
     janet_ev_deinit_common();
     free(janet_vm_fds);
+    close(janet_vm_selfpipe[0]);
+    close(janet_vm_selfpipe[1]);
     janet_vm_fds = NULL;
 }
 
@@ -1691,9 +1778,7 @@ static Janet cfun_ev_call(int32_t argc, Janet *argv) {
     return janet_wrap_fiber(fiber);
 }
 
-static Janet cfun_ev_sleep(int32_t argc, Janet *argv) {
-    janet_fixarity(argc, 1);
-    double sec = janet_getnumber(argv, 0);
+JANET_NO_RETURN void janet_sleep_await(double sec) {
     JanetTimeout to;
     to.when = ts_delta(ts_now(), sec);
     to.fiber = janet_vm_root_fiber;
@@ -1703,6 +1788,12 @@ static Janet cfun_ev_sleep(int32_t argc, Janet *argv) {
     janet_await();
 }
 
+static Janet cfun_ev_sleep(int32_t argc, Janet *argv) {
+    janet_fixarity(argc, 1);
+    double sec = janet_getnumber(argv, 0);
+    janet_sleep_await(sec);
+}
+
 static Janet cfun_ev_cancel(int32_t argc, Janet *argv) {
     janet_fixarity(argc, 2);
     JanetFiber *fiber = janet_getfiber(argv, 0);

src/core/os.c

@@ -185,6 +185,7 @@ static Janet os_exit(int32_t argc, Janet *argv) {
 #ifndef JANET_REDUCED_OS
 
 #ifndef JANET_NO_PROCESSES
+
 /* Get env for os_execute */
 static char **os_execute_env(int32_t argc, const Janet *argv) {
     char **envp = NULL;
@@ -319,6 +320,8 @@ static JanetBuffer *os_exec_escape(JanetView args) {
 static const JanetAbstractType ProcAT;
 #define JANET_PROC_CLOSED 1
 #define JANET_PROC_WAITED 2
+#define JANET_PROC_WAITING 4
+#define JANET_PROC_ERROR_NONZERO 8
 typedef struct {
     int flags;
 #ifdef JANET_WINDOWS
@@ -332,6 +335,7 @@ typedef struct {
     JanetStream *in;
     JanetStream *out;
     JanetStream *err;
+    JanetFiber *fiber;
 #else
     JanetFile *in;
     JanetFile *out;
@@ -339,9 +343,82 @@ typedef struct {
 #endif
 } JanetProc;
 
+#ifdef JANET_EV
+
+JANET_THREAD_LOCAL JanetProc **janet_vm_waiting_procs = NULL;
+JANET_THREAD_LOCAL size_t janet_vm_proc_count = 0;
+JANET_THREAD_LOCAL size_t janet_vm_proc_cap = 0;
+
+/* Map pids to JanetProc to allow for lookup after a call to
+ * waitpid. */
+static void janet_add_waiting_proc(JanetProc *proc) {
+    if (janet_vm_proc_count == janet_vm_proc_cap) {
+        size_t newcap = (janet_vm_proc_count + 1) * 2;
+        if (newcap < 16) newcap = 16;
+        JanetProc **newprocs = realloc(janet_vm_waiting_procs, sizeof(JanetProc *) * newcap);
+        if (NULL == newprocs) {
+            JANET_OUT_OF_MEMORY;
+        }
+        janet_vm_waiting_procs = newprocs;
+        janet_vm_proc_cap = newcap;
+    }
+    janet_vm_waiting_procs[janet_vm_proc_count++] = proc;
+    janet_gcroot(janet_wrap_abstract(proc));
+    janet_ev_inc_refcount();
+}
+
+static void janet_remove_waiting_proc(JanetProc *proc) {
+    for (size_t i = 0; i < janet_vm_proc_count; i++) {
+        if (janet_vm_waiting_procs[i] == proc) {
+            janet_vm_waiting_procs[i] = janet_vm_waiting_procs[--janet_vm_proc_count];
+            janet_gcunroot(janet_wrap_abstract(proc));
+            janet_ev_dec_refcount();
+            return;
+        }
+    }
+}
+
+static JanetProc *janet_lookup_proc(pid_t pid) {
+    for (size_t i = 0; i < janet_vm_proc_count; i++) {
+        if (janet_vm_waiting_procs[i]->pid == pid) {
+            return janet_vm_waiting_procs[i];
+        }
+    }
+    return NULL;
+}
+
+void janet_schedule_pid(pid_t pid, int status) {
+    /* Use POSIX shell semantics for interpreting signals */
+    if (WIFEXITED(status)) {
+        status = WEXITSTATUS(status);
+    } else if (WIFSTOPPED(status)) {
+        status = WSTOPSIG(status) + 128;
+    } else {
+        status = WTERMSIG(status) + 128;
+    }
+    JanetProc *proc = janet_lookup_proc(pid);
+    if (NULL == proc) return;
+    proc->return_code = (int32_t) status;
+    proc->flags |= JANET_PROC_WAITED;
+    proc->flags &= ~JANET_PROC_WAITING;
+    if ((status != 0) && (proc->flags & JANET_PROC_ERROR_NONZERO)) {
+        JanetString s = janet_formatc("command failed with non-zero exit code %d", status);
+        janet_cancel(proc->fiber, janet_wrap_string(s));
+    } else {
+        janet_schedule(proc->fiber, janet_wrap_integer(status));
+    }
+    janet_remove_waiting_proc(proc);
+}
+#endif
+
 static int janet_proc_gc(void *p, size_t s) {
     (void) s;
     JanetProc *proc = (JanetProc *) p;
+#ifdef JANET_EV
+    if (proc->flags & JANET_PROC_WAITING) {
+        janet_remove_waiting_proc(proc);
+    }
+#endif
 #ifdef JANET_WINDOWS
     if (!(proc->flags & JANET_PROC_CLOSED)) {
         CloseHandle(proc->pHandle);
@@ -364,13 +441,27 @@ static int janet_proc_mark(void *p, size_t s) {
     if (NULL != proc->in) janet_mark(janet_wrap_abstract(proc->in));
     if (NULL != proc->out) janet_mark(janet_wrap_abstract(proc->out));
     if (NULL != proc->err) janet_mark(janet_wrap_abstract(proc->err));
+#ifdef JANET_EV
+    if (NULL != proc->fiber) janet_mark(janet_wrap_fiber(proc->fiber));
+#endif
     return 0;
 }
 
+#ifdef JANET_EV
+JANET_NO_RETURN
+#endif
 static Janet os_proc_wait_impl(JanetProc *proc) {
-    if (proc->flags & JANET_PROC_WAITED) {
-        janet_panicf("cannot wait on process that has already finished");
+    if (proc->flags & (JANET_PROC_WAITED | JANET_PROC_WAITING)) {
+        janet_panicf("cannot wait twice on a process");
     }
+#ifdef JANET_EV
+    /* Event loop implementation */
+    proc->fiber = janet_root_fiber();
+    proc->flags |= JANET_PROC_WAITING;
+    janet_add_waiting_proc(proc);
+    janet_await();
+#else
+    /* Non evented implementation */
     proc->flags |= JANET_PROC_WAITED;
     int status = 0;
 #ifdef JANET_WINDOWS
@@ -386,6 +477,7 @@ static Janet os_proc_wait_impl(JanetProc *proc) {
 #endif
     proc->return_code = (int32_t) status;
     return janet_wrap_integer(proc->return_code);
+#endif
 }
 
 static Janet os_proc_wait(int32_t argc, Janet *argv) {
@@ -575,7 +667,7 @@ static JanetFile *get_stdio_for_handle(JanetHandle handle, void *orig, int iswri
 }
 #endif
 
-static Janet os_execute_impl(int32_t argc, Janet *argv, int is_async) {
+static Janet os_execute_impl(int32_t argc, Janet *argv, int is_spawn) {
     janet_arity(argc, 1, 3);
 
     /* Get flags */
@@ -713,7 +805,7 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, int is_async) {
     tHandle = processInfo.hThread;
 
     /* Wait and cleanup immedaitely */
-    if (!is_async) {
+    if (!is_spawn) {
         DWORD code;
         WaitForSingleObject(pHandle, INFINITE);
         GetExitCodeProcess(pHandle, &code);
@@ -781,45 +873,42 @@ static Janet os_execute_impl(int32_t argc, Janet *argv, int is_async) {
     if (status) {
         os_execute_cleanup(envp, child_argv);
         janet_panicf("%p: %s", argv[0], strerror(errno));
-    } else if (is_async) {
+    } else if (is_spawn) {
         /* Get process handle */
         os_execute_cleanup(envp, child_argv);
     } else {
         /* Wait to complete */
-        waitpid(pid, &status, 0);
         os_execute_cleanup(envp, child_argv);
-        /* Use POSIX shell semantics for interpreting signals */
-        if (WIFEXITED(status)) {
-            status = WEXITSTATUS(status);
-        } else if (WIFSTOPPED(status)) {
-            status = WSTOPSIG(status) + 128;
-        } else {
-            status = WTERMSIG(status) + 128;
-        }
     }
 
 #endif
-    if (is_async) {
-        JanetProc *proc = janet_abstract(&ProcAT, sizeof(JanetProc));
-        proc->return_code = -1;
+    JanetProc *proc = janet_abstract(&ProcAT, sizeof(JanetProc));
+    proc->return_code = -1;
 #ifdef JANET_WINDOWS
-        proc->pHandle = pHandle;
-        proc->tHandle = tHandle;
+    proc->pHandle = pHandle;
+    proc->tHandle = tHandle;
 #else
-        proc->pid = pid;
+    proc->pid = pid;
 #endif
-        proc->in = get_stdio_for_handle(new_in, orig_in, 0);
-        proc->out = get_stdio_for_handle(new_out, orig_out, 1);
-        proc->err = get_stdio_for_handle(new_err, orig_err, 1);
-        proc->flags = 0;
-        if (proc->in == NULL || proc->out == NULL || proc->err == NULL) {
-            janet_panic("failed to construct proc");
-        }
+    proc->in = get_stdio_for_handle(new_in, orig_in, 0);
+    proc->out = get_stdio_for_handle(new_out, orig_out, 1);
+    proc->err = get_stdio_for_handle(new_err, orig_err, 1);
+    proc->flags = 0;
+    if (proc->in == NULL || proc->out == NULL || proc->err == NULL) {
+        janet_panic("failed to construct proc");
+    }
+    if (janet_flag_at(flags, 2)) {
+        proc->flags |= JANET_PROC_ERROR_NONZERO;
+    }
+
+    if (is_spawn) {
         return janet_wrap_abstract(proc);
-    } else if (janet_flag_at(flags, 2) && status) {
-        janet_panicf("command failed with non-zero exit code %d", status);
     } else {
-        return janet_wrap_integer(status);
+#ifdef JANET_EV
+        os_proc_wait_impl(proc);
+#else
+        return os_proc_wait_impl(proc);
+#endif
     }
 }
 
@@ -2069,6 +2158,17 @@ static const JanetReg os_cfuns[] = {
     {NULL, NULL, NULL}
 };
 
+void janet_os_deinit(void) {
+#ifndef JANET_NO_PROCESSES
+#ifdef JANET_EV
+    free(janet_vm_waiting_procs);
+    janet_vm_waiting_procs = NULL;
+    janet_vm_proc_count = 0;
+    janet_vm_proc_cap = 0;
+#endif
+#endif
+}
+
 /* Module entry point */
 void janet_lib_os(JanetTable *env) {
 #if !defined(JANET_REDUCED_OS) && defined(JANET_WINDOWS) && defined(JANET_THREADS)
@@ -2078,6 +2178,13 @@ void janet_lib_os(JanetTable *env) {
         InitializeCriticalSection(&env_lock);
         env_lock_initialized = 1;
     }
+#endif
+#ifndef JANET_NO_PROCESSES
+#ifdef JANET_EV
+    janet_vm_waiting_procs = NULL;
+    janet_vm_proc_count = 0;
+    janet_vm_proc_cap = 0;
+#endif
 #endif
     janet_core_cfuns(env, NULL, os_cfuns);
 }

src/core/state.h

@@ -111,4 +111,6 @@ void janet_ev_init(void);
 void janet_ev_deinit(void);
 #endif
 
+void janet_os_deinit(void);
+
 #endif /* JANET_STATE_H_defined */

src/core/util.h

@@ -146,6 +146,7 @@ extern const JanetAbstractType janet_address_type;
 void janet_lib_ev(JanetTable *env);
 void janet_ev_mark(void);
 int janet_make_pipe(JanetHandle handles[2]);
+void janet_schedule_pid(pid_t pid, int status);
 #endif
 
 #endif

src/core/vm.c

@@ -1478,7 +1478,6 @@ int janet_init(void) {
     janet_vm_fiber = NULL;
     janet_vm_root_fiber = NULL;
     janet_vm_stackn = 0;
-    /* Threads */
 #ifdef JANET_THREADS
     janet_threads_init();
 #endif
@@ -1506,6 +1505,7 @@ void janet_deinit(void) {
     free(janet_vm_traversal_base);
     janet_vm_fiber = NULL;
     janet_vm_root_fiber = NULL;
+    janet_os_deinit();
 #ifdef JANET_THREADS
     janet_threads_deinit();
 #endif

src/include/janet.h

@@ -1279,10 +1279,13 @@ JANET_API JanetListenerState *janet_listen(JanetStream *stream, JanetListener be
 
 /* Shorthand for yielding to event loop in C */
 JANET_NO_RETURN JANET_API void janet_await(void);
+JANET_NO_RETURN JANET_API void janet_sleep_await(double sec);
 
 /* For use inside listeners - adds a timeout to the current fiber, such that
  * it will be resumed after sec seconds if no other event schedules the current fiber. */
 JANET_API void janet_addtimeout(double sec);
+JANET_API void janet_ev_inc_refcount(void);
+JANET_API void janet_ev_dec_refcount(void);
 
 /* Get last error from a an IO operation */
 JANET_API Janet janet_ev_lasterr(void);

test/suite0009.janet

@@ -40,7 +40,7 @@
 # or else the first read can fail. Might be a strange windows
 # "bug", but needs further investigating. Otherwise, `build_win test`
 # can sometimes fail on windows, leading to flaky testing.
-(ev/sleep 0.2)
+(ev/sleep 0.3)
 
 (defn test-echo [msg]
   (with [conn (net/connect "127.0.0.1" "8000")]
@@ -59,6 +59,7 @@
 (var pipe-counter 0)
 (def chan (ev/chan 10))
 (let [[reader writer] (os/pipe)]
+  (ev/sleep 0.3)
   (ev/spawn
     (while (ev/read reader 3)
       (++ pipe-counter))