Merge pull request #510 from pietern/2.6-eventport

Support for Illumos event ports

3 files changed, 305 insertions, 5 deletions

diff --git a/src/ae.c b/src/ae.c
index 668277a78..c58c4b74b 100644
--- a/src/ae.c
+++ b/src/ae.c
@@ -44,13 +44,17 @@
 
 /* Include the best multiplexing layer supported by this system.
  * The following should be ordered by performances, descending. */
-#ifdef HAVE_EPOLL
-#include "ae_epoll.c"
+#ifdef HAVE_EVPORT
+#include "ae_evport.c"
 #else
-    #ifdef HAVE_KQUEUE
-    #include "ae_kqueue.c"
+    #ifdef HAVE_EPOLL
+    #include "ae_epoll.c"
     #else
-    #include "ae_select.c"
+        #ifdef HAVE_KQUEUE
+        #include "ae_kqueue.c"
+        #else
+        #include "ae_select.c"
+        #endif
     #endif
 #endif
 
diff --git a/src/ae_evport.c b/src/ae_evport.c
new file mode 100644
index 000000000..5b6602d02
--- /dev/null
+++ b/src/ae_evport.c
@@ -0,0 +1,289 @@
+/* ae.c module for illumos event ports.
+ * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Released under the BSD license. See the COPYING file for more info. */
+
+#include <assert.h>
+#include <errno.h>
+#include <port.h>
+#include <poll.h>
+
+#include <sys/types.h>
+#include <sys/time.h>
+
+#include <stdio.h>
+
+static int evport_debug = 0;
+
+/*
+ * This file implements the ae API using event ports, present on Solaris-based
+ * systems since Solaris 10.  Using the event port interface, we associate file
+ * descriptors with the port.  Each association also includes the set of poll(2)
+ * events that the consumer is interested in (e.g., POLLIN and POLLOUT).
+ *
+ * There's one tricky piece to this implementation: when we return events via
+ * aeApiPoll, the corresponding file descriptors become dissociated from the
+ * port.  This is necessary because poll events are level-triggered, so if the
+ * fd didn't become dissociated, it would immediately fire another event since
+ * the underlying state hasn't changed yet.  We must reassociate the file
+ * descriptor, but only after we know that our caller has actually read from it.
+ * The ae API does not tell us exactly when that happens, but we do know that
+ * it must happen by the time aeApiPoll is called again.  Our solution is to
+ * keep track of the last fds returned by aeApiPoll and reassociate them next
+ * time aeApiPoll is invoked.
+ *
+ * To summarize, in this module, each fd association is EITHER (a) represented
+ * only via the in-kernel assocation OR (b) represented by pending_fds and
+ * pending_masks.  (b) is only true for the last fds we returned from aeApiPoll,
+ * and only until we enter aeApiPoll again (at which point we restore the
+ * in-kernel association).
+ */
+#define MAX_EVENT_BATCHSZ 512
+
+typedef struct aeApiState {
+    int     portfd;                             /* event port */
+    int     npending;                           /* # of pending fds */
+    int     pending_fds[MAX_EVENT_BATCHSZ];     /* pending fds */
+    int     pending_masks[MAX_EVENT_BATCHSZ];   /* pending fds' masks */
+} aeApiState;
+
+static int aeApiCreate(aeEventLoop *eventLoop) {
+    int i;
+    aeApiState *state = zmalloc(sizeof(aeApiState));
+    if (!state) return -1;
+
+    state->portfd = port_create();
+    if (state->portfd == -1) {
+        zfree(state);
+        return -1;
+    }
+
+    state->npending = 0;
+
+    for (i = 0; i < MAX_EVENT_BATCHSZ; i++) {
+        state->pending_fds[i] = -1;
+        state->pending_masks[i] = AE_NONE;
+    }
+
+    eventLoop->apidata = state;
+    return 0;
+}
+
+static void aeApiFree(aeEventLoop *eventLoop) {
+    aeApiState *state = eventLoop->apidata;
+
+    close(state->portfd);
+    zfree(state);
+}
+
+static int aeApiLookupPending(aeApiState *state, int fd) {
+    int i;
+
+    for (i = 0; i < state->npending; i++) {
+        if (state->pending_fds[i] == fd)
+            return (i);
+    }
+
+    return (-1);
+}
+
+/*
+ * Helper function to invoke port_associate for the given fd and mask.
+ */
+static int aeApiAssociate(const char *where, int portfd, int fd, int mask) {
+    int events = 0;
+    int rv, err;
+
+    if (mask & AE_READABLE)
+        events |= POLLIN;
+    if (mask & AE_WRITABLE)
+        events |= POLLOUT;
+
+    if (evport_debug)
+        fprintf(stderr, "%s: port_associate(%d, 0x%x) = ", where, fd, events);
+
+    rv = port_associate(portfd, PORT_SOURCE_FD, fd, events,
+        (void *)(uintptr_t)mask);
+    err = errno;
+
+    if (evport_debug)
+        fprintf(stderr, "%d (%s)\n", rv, rv == 0 ? "no error" : strerror(err));
+
+    if (rv == -1) {
+        fprintf(stderr, "%s: port_associate: %s\n", where, strerror(err));
+
+        if (err == EAGAIN)
+            fprintf(stderr, "aeApiAssociate: event port limit exceeded.");
+    }
+
+    return rv;
+}
+
+static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {
+    aeApiState *state = eventLoop->apidata;
+    int fullmask, pfd;
+
+    if (evport_debug)
+        fprintf(stderr, "aeApiAddEvent: fd %d mask 0x%x\n", fd, mask);
+
+    /*
+     * Since port_associate's "events" argument replaces any existing events, we
+     * must be sure to include whatever events are already associated when
+     * we call port_associate() again.
+     */
+    fullmask = mask | eventLoop->events[fd].mask;
+    pfd = aeApiLookupPending(state, fd);
+
+    if (pfd != -1) {
+        /*
+         * This fd was recently returned from aeApiPoll.  It should be safe to
+         * assume that the consumer has processed that poll event, but we play
+         * it safer by simply updating pending_mask.  The fd will be
+         * reassociated as usual when aeApiPoll is called again.
+         */
+        if (evport_debug)
+            fprintf(stderr, "aeApiAddEvent: adding to pending fd %d\n", fd);
+        state->pending_masks[pfd] |= fullmask;
+        return 0;
+    }
+
+    return (aeApiAssociate("aeApiAddEvent", state->portfd, fd, fullmask));
+}
+
+static void aeApiDelEvent(aeEventLoop *eventLoop, int fd, int mask) {
+    aeApiState *state = eventLoop->apidata;
+    int fullmask, pfd;
+
+    if (evport_debug)
+        fprintf(stderr, "del fd %d mask 0x%x\n", fd, mask);
+
+    pfd = aeApiLookupPending(state, fd);
+
+    if (pfd != -1) {
+        if (evport_debug)
+            fprintf(stderr, "deleting event from pending fd %d\n", fd);
+
+        /*
+         * This fd was just returned from aeApiPoll, so it's not currently
+         * associated with the port.  All we need to do is update
+         * pending_mask appropriately.
+         */
+        state->pending_masks[pfd] &= ~mask;
+
+        if (state->pending_masks[pfd] == AE_NONE)
+            state->pending_fds[pfd] = -1;
+
+        return;
+    }
+
+    /*
+     * The fd is currently associated with the port.  Like with the add case
+     * above, we must look at the full mask for the file descriptor before
+     * updating that association.  We don't have a good way of knowing what the
+     * events are without looking into the eventLoop state directly.  We rely on
+     * the fact that our caller has already updated the mask in the eventLoop.
+     */
+
+    fullmask = eventLoop->events[fd].mask;
+    if (fullmask == AE_NONE) {
+        /*
+         * We're removing *all* events, so use port_dissociate to remove the
+         * association completely.  Failure here indicates a bug.
+         */
+        if (evport_debug)
+            fprintf(stderr, "aeApiDelEvent: port_dissociate(%d)\n", fd);
+
+        if (port_dissociate(state->portfd, PORT_SOURCE_FD, fd) != 0) {
+            perror("aeApiDelEvent: port_dissociate");
+            abort(); /* will not return */
+        }
+    } else if (aeApiAssociate("aeApiDelEvent", state->portfd, fd,
+        fullmask) != 0) {
+        /*
+         * ENOMEM is a potentially transient condition, but the kernel won't
+         * generally return it unless things are really bad.  EAGAIN indicates
+         * we've reached an resource limit, for which it doesn't make sense to
+         * retry (counterintuitively).  All other errors indicate a bug.  In any
+         * of these cases, the best we can do is to abort.
+         */
+        abort(); /* will not return */
+    }
+}
+
+static int aeApiPoll(aeEventLoop *eventLoop, struct timeval *tvp) {
+    aeApiState *state = eventLoop->apidata;
+    struct timespec timeout, *tsp;
+    int mask, i;
+    uint_t nevents;
+    port_event_t event[MAX_EVENT_BATCHSZ];
+
+    /*
+     * If we've returned fd events before, we must reassociate them with the
+     * port now, before calling port_get().  See the block comment at the top of
+     * this file for an explanation of why.
+     */
+    for (i = 0; i < state->npending; i++) {
+        if (state->pending_fds[i] == -1)
+            /* This fd has since been deleted. */
+            continue;
+
+        if (aeApiAssociate("aeApiPoll", state->portfd,
+            state->pending_fds[i], state->pending_masks[i]) != 0) {
+            /* See aeApiDelEvent for why this case is fatal. */
+            abort();
+        }
+
+        state->pending_masks[i] = AE_NONE;
+        state->pending_fds[i] = -1;
+    }
+
+    state->npending = 0;
+
+    if (tvp != NULL) {
+        timeout.tv_sec = tvp->tv_sec;
+        timeout.tv_nsec = tvp->tv_usec * 1000;
+        tsp = &timeout;
+    } else {
+        tsp = NULL;
+    }
+
+    /*
+     * port_getn can return with errno == ETIME having returned some events (!).
+     * So if we get ETIME, we check nevents, too.
+     */
+    nevents = 1;
+    if (port_getn(state->portfd, event, MAX_EVENT_BATCHSZ, &nevents,
+        tsp) == -1 && (errno != ETIME || nevents == 0)) {
+        if (errno == ETIME || errno == EINTR)
+            return 0;
+
+        /* Any other error indicates a bug. */
+        perror("aeApiPoll: port_get");
+        abort();
+    }
+
+    state->npending = nevents;
+
+    for (i = 0; i < nevents; i++) {
+            mask = 0;
+            if (event[i].portev_events & POLLIN)
+                mask |= AE_READABLE;
+            if (event[i].portev_events & POLLOUT)
+                mask |= AE_WRITABLE;
+
+            eventLoop->fired[i].fd = event[i].portev_object;
+            eventLoop->fired[i].mask = mask;
+
+            if (evport_debug)
+                fprintf(stderr, "aeApiPoll: fd %d mask 0x%x\n",
+                    (int)event[i].portev_object, mask);
+
+            state->pending_fds[i] = event[i].portev_object;
+            state->pending_masks[i] = (uintptr_t)event[i].portev_user;
+    }
+
+    return nevents;
+}
+
+static char *aeApiName(void) {
+    return "evport";
+}
diff --git a/src/config.h b/src/config.h
index 136fd40c4..28ef37d6e 100644
--- a/src/config.h
+++ b/src/config.h
@@ -38,6 +38,13 @@
 #define HAVE_KQUEUE 1
 #endif
 
+#ifdef __sun
+#include <sys/feature_tests.h>
+#ifdef _DTRACE_VERSION
+#define HAVE_EVPORT 1
+#endif
+#endif
+
 /* Define aof_fsync to fdatasync() in Linux and fsync() for all the rest */
 #ifdef __linux__
 #define aof_fsync fdatasync