Smarter pollset/pollset_set propagation

For some definition of "smart"... client_channel simply passes along
pollset/pollset_set, removing the need to instantiate a pollset_set in
the subchannel_call_holder: it's now up to the LB policies to handle the
pollset/pollset_set.

9 files changed, 165 insertions, 41 deletions

diff --git a/src/core/ext/client_config/client_channel.c b/src/core/ext/client_config/client_channel.c
index 87abfea5ff..68a203820b 100644
--- a/src/core/ext/client_config/client_channel.c
+++ b/src/core/ext/client_config/client_channel.c
@@ -368,9 +368,11 @@ static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *elemp,
     int r;
     GRPC_LB_POLICY_REF(lb_policy, "cc_pick_subchannel");
     gpr_mu_unlock(&chand->mu_config);
-    r = grpc_lb_policy_pick(exec_ctx, lb_policy, calld->pollset_set,
-                            initial_metadata, initial_metadata_flags,
-                            connected_subchannel, on_ready);
+    GPR_ASSERT((calld->pollset != NULL) + (calld->pollset_set != NULL) == 1);
+    r = grpc_lb_policy_pick(exec_ctx, lb_policy, calld->pollset,
+                            calld->pollset_set, initial_metadata,
+                            initial_metadata_flags, connected_subchannel,
+                            on_ready);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "cc_pick_subchannel");
     return r;
   }
@@ -453,14 +455,8 @@ static void cc_set_pollset_or_pollset_set(
   GPR_ASSERT(pollset != NULL || pollset_set_alternative != NULL);
 
   call_data *calld = elem->call_data;
-  if (pollset != NULL) {
-    calld->pollset = pollset;
-    grpc_pollset_set_add_pollset(exec_ctx, calld->pollset_set, pollset);
-  } else if (pollset_set_alternative != NULL) {
-    calld->pollset = NULL;
-    grpc_pollset_set_add_pollset_set(exec_ctx, calld->pollset_set,
-                                     pollset_set_alternative);
-  }
+  calld->pollset = pollset;
+  calld->pollset_set = pollset_set_alternative;
 }
 
 const grpc_channel_filter grpc_client_channel_filter = {
diff --git a/src/core/ext/client_config/lb_policy.c b/src/core/ext/client_config/lb_policy.c
index 1e4e0077e6..96342c7c7d 100644
--- a/src/core/ext/client_config/lb_policy.c
+++ b/src/core/ext/client_config/lb_policy.c
@@ -99,12 +99,14 @@ void grpc_lb_policy_weak_unref(grpc_exec_ctx *exec_ctx,
 }
 
 int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        grpc_pollset_set *pollset_set,
+                        grpc_pollset *pollset,
+                        grpc_pollset_set *pollset_set_alternative,
                         grpc_metadata_batch *initial_metadata,
                         uint32_t initial_metadata_flags,
                         grpc_connected_subchannel **target,
                         grpc_closure *on_complete) {
-  return policy->vtable->pick(exec_ctx, policy, pollset_set, initial_metadata,
+  return policy->vtable->pick(exec_ctx, policy, pollset,
+                              pollset_set_alternative, initial_metadata,
                               initial_metadata_flags, target, on_complete);
 }
 
diff --git a/src/core/ext/client_config/lb_policy.h b/src/core/ext/client_config/lb_policy.h
index d5c578836b..e9bb1850e7 100644
--- a/src/core/ext/client_config/lb_policy.h
+++ b/src/core/ext/client_config/lb_policy.h
@@ -59,7 +59,7 @@ struct grpc_lb_policy_vtable {
 
   /** implement grpc_lb_policy_pick */
   int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-              grpc_pollset_set *pollset_set,
+              grpc_pollset *pollset, grpc_pollset_set *pollset_set_alternative,
               grpc_metadata_batch *initial_metadata,
               uint32_t initial_metadata_flags,
               grpc_connected_subchannel **target, grpc_closure *on_complete);
@@ -125,7 +125,8 @@ void grpc_lb_policy_init(grpc_lb_policy *policy,
     \a target.
     Picking can be asynchronous. Any IO should be done under \a pollset. */
 int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        grpc_pollset_set *pollset_set,
+                        grpc_pollset *pollset,
+                        grpc_pollset_set *pollset_set_alternative,
                         grpc_metadata_batch *initial_metadata,
                         uint32_t initial_metadata_flags,
                         grpc_connected_subchannel **target,
diff --git a/src/core/ext/client_config/subchannel_call_holder.c b/src/core/ext/client_config/subchannel_call_holder.c
index c6f4b8f373..e07dd1a621 100644
--- a/src/core/ext/client_config/subchannel_call_holder.c
+++ b/src/core/ext/client_config/subchannel_call_holder.c
@@ -68,7 +68,7 @@ void grpc_subchannel_call_holder_init(
   holder->waiting_ops_capacity = 0;
   holder->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
   holder->owning_call = owning_call;
-  holder->pollset_set = grpc_pollset_set_create();
+  holder->pollset_set = NULL;
 }
 
 void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
@@ -82,7 +82,6 @@ void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
   gpr_mu_destroy(&holder->mu);
   GPR_ASSERT(holder->waiting_ops_count == 0);
   gpr_free(holder->waiting_ops);
-  grpc_pollset_set_destroy(holder->pollset_set);
 }
 
 void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/ext/lb_policy/common.c b/src/core/ext/lb_policy/common.c
new file mode 100644
index 0000000000..bfb6aace87
--- /dev/null
+++ b/src/core/ext/lb_policy/common.c
@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * 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 Google Inc. 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.
+ *
+ */
+
+#include <grpc/support/log.h>
+
+#include "src/core/ext/lb_policy/common.h"
+
+void add_pollset_or_pollset_set_alternative(
+    grpc_exec_ctx *exec_ctx, grpc_pollset_set *interested_parties,
+    grpc_pollset *pollset, grpc_pollset_set *pollset_set_alternative) {
+  if (pollset != NULL) {
+    GPR_ASSERT(pollset_set_alternative == NULL);
+    grpc_pollset_set_add_pollset(exec_ctx, interested_parties, pollset);
+  } else {
+    GPR_ASSERT(pollset_set_alternative != NULL);
+    grpc_pollset_set_add_pollset_set(exec_ctx, interested_parties,
+                                     pollset_set_alternative);
+  }
+}
+
+void del_pollset_or_pollset_set_alternative(
+    grpc_exec_ctx *exec_ctx, grpc_pollset_set *interested_parties,
+    grpc_pollset *pollset, grpc_pollset_set *pollset_set_alternative) {
+  if (pollset != NULL) {
+    GPR_ASSERT(pollset_set_alternative == NULL);
+    grpc_pollset_set_del_pollset(exec_ctx, interested_parties, pollset);
+  } else {
+    GPR_ASSERT(pollset_set_alternative != NULL);
+    grpc_pollset_set_del_pollset_set(exec_ctx, interested_parties,
+                                     pollset_set_alternative);
+  }
+}
diff --git a/src/core/ext/lb_policy/common.h b/src/core/ext/lb_policy/common.h
new file mode 100644
index 0000000000..1ace967328
--- /dev/null
+++ b/src/core/ext/lb_policy/common.h
@@ -0,0 +1,48 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * 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 Google Inc. 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 GRPC_CORE_EXT_LB_POLICY_COMMON_H
+#define GRPC_CORE_EXT_LB_POLICY_COMMON_H
+
+#include "src/core/lib/iomgr/pollset.h"
+#include "src/core/lib/iomgr/pollset_set.h"
+
+void add_pollset_or_pollset_set_alternative(
+    grpc_exec_ctx *exec_ctx, grpc_pollset_set *interested_parties,
+    grpc_pollset *pollset, grpc_pollset_set *pollset_set_alternative);
+
+void del_pollset_or_pollset_set_alternative(
+    grpc_exec_ctx *exec_ctx, grpc_pollset_set *interested_parties,
+    grpc_pollset *pollset, grpc_pollset_set *pollset_set_alternative);
+
+#endif /* GRPC_CORE_EXT_LB_POLICY_COMMON_H */
diff --git a/src/core/ext/lb_policy/pick_first/pick_first.c b/src/core/ext/lb_policy/pick_first/pick_first.c
index 0ffa003946..f6613298be 100644
--- a/src/core/ext/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/lb_policy/pick_first/pick_first.c
@@ -35,11 +35,13 @@
 
 #include <grpc/support/alloc.h>
 #include "src/core/ext/client_config/lb_policy_registry.h"
+#include "src/core/ext/lb_policy/common.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
 typedef struct pending_pick {
   struct pending_pick *next;
-  grpc_pollset_set *pollset_set;
+  grpc_pollset *pollset;
+  grpc_pollset_set *pollset_set_alternative;
   uint32_t initial_metadata_flags;
   grpc_connected_subchannel **target;
   grpc_closure *on_complete;
@@ -118,8 +120,9 @@ static void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   while (pp != NULL) {
     pending_pick *next = pp->next;
     *pp->target = NULL;
-    grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                     pp->pollset_set);
+    del_pollset_or_pollset_set_alternative(exec_ctx, p->base.interested_parties,
+                                           pp->pollset,
+                                           pp->pollset_set_alternative);
     grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, true, NULL);
     gpr_free(pp);
     pp = next;
@@ -136,8 +139,9 @@ static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   while (pp != NULL) {
     pending_pick *next = pp->next;
     if (pp->target == target) {
-      grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                       pp->pollset_set);
+      del_pollset_or_pollset_set_alternative(
+          exec_ctx, p->base.interested_parties, pp->pollset,
+          pp->pollset_set_alternative);
       *target = NULL;
       grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL);
       gpr_free(pp);
@@ -162,8 +166,9 @@ static void pf_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                       pp->pollset_set);
+      del_pollset_or_pollset_set_alternative(
+          exec_ctx, p->base.interested_parties, pp->pollset,
+          pp->pollset_set_alternative);
       grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL);
       gpr_free(pp);
     } else {
@@ -196,7 +201,8 @@ static void pf_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
 }
 
 static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   grpc_pollset_set *pollset_set,
+                   grpc_pollset *pollset,
+                   grpc_pollset_set *pollset_set_alternative,
                    grpc_metadata_batch *initial_metadata,
                    uint32_t initial_metadata_flags,
                    grpc_connected_subchannel **target,
@@ -222,11 +228,12 @@ static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_pollset_set_add_pollset_set(exec_ctx, p->base.interested_parties,
-                                     pollset_set);
+    add_pollset_or_pollset_set_alternative(exec_ctx, p->base.interested_parties,
+                                           pollset, pollset_set_alternative);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollset_set = pollset_set;
+    pp->pollset = pollset;
+    pp->pollset_set_alternative = pollset_set_alternative;
     pp->target = target;
     pp->initial_metadata_flags = initial_metadata_flags;
     pp->on_complete = on_complete;
@@ -306,8 +313,9 @@ static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
           *pp->target = selected;
-          grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                           pp->pollset_set);
+          del_pollset_or_pollset_set_alternative(
+              exec_ctx, p->base.interested_parties, pp->pollset,
+              pp->pollset_set_alternative);
           grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, true, NULL);
           gpr_free(pp);
         }
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index 78ac61923f..f4e3d60a83 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -36,6 +36,7 @@
 #include <grpc/support/alloc.h>
 
 #include "src/core/ext/client_config/lb_policy_registry.h"
+#include "src/core/ext/lb_policy/common.h"
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
@@ -48,7 +49,8 @@ int grpc_lb_round_robin_trace = 0;
  * Once a pick is available, \a target is updated and \a on_complete called. */
 typedef struct pending_pick {
   struct pending_pick *next;
-  grpc_pollset_set *pollset_set;
+  grpc_pollset *pollset;
+  grpc_pollset_set *pollset_set_alternative;
   uint32_t initial_metadata_flags;
   grpc_connected_subchannel **target;
   grpc_closure *on_complete;
@@ -262,8 +264,9 @@ static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
   while (pp != NULL) {
     pending_pick *next = pp->next;
     if (pp->target == target) {
-      grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                       pp->pollset_set);
+      del_pollset_or_pollset_set_alternative(
+          exec_ctx, p->base.interested_parties, pp->pollset,
+          pp->pollset_set_alternative);
       *target = NULL;
       grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL);
       gpr_free(pp);
@@ -288,8 +291,9 @@ static void rr_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     pending_pick *next = pp->next;
     if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
         initial_metadata_flags_eq) {
-      grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                       pp->pollset_set);
+      del_pollset_or_pollset_set_alternative(
+          exec_ctx, p->base.interested_parties, pp->pollset,
+          pp->pollset_set_alternative);
       *pp->target = NULL;
       grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL);
       gpr_free(pp);
@@ -329,7 +333,8 @@ static void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
 }
 
 static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   grpc_pollset_set *pollset_set,
+                   grpc_pollset *pollset,
+                   grpc_pollset_set *pollset_set_alternative,
                    grpc_metadata_batch *initial_metadata,
                    uint32_t initial_metadata_flags,
                    grpc_connected_subchannel **target,
@@ -353,11 +358,12 @@ static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     if (!p->started_picking) {
       start_picking(exec_ctx, p);
     }
-    grpc_pollset_set_add_pollset_set(exec_ctx, p->base.interested_parties,
-                                     pollset_set);
+    add_pollset_or_pollset_set_alternative(exec_ctx, p->base.interested_parties,
+                                           pollset, pollset_set_alternative);
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
-    pp->pollset_set = pollset_set;
+    pp->pollset = pollset;
+    pp->pollset_set_alternative = pollset_set_alternative;
     pp->target = target;
     pp->on_complete = on_complete;
     pp->initial_metadata_flags = initial_metadata_flags;
@@ -406,8 +412,9 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
                     "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
                     selected->subchannel, selected);
           }
-          grpc_pollset_set_del_pollset_set(exec_ctx, p->base.interested_parties,
-                                           pp->pollset_set);
+          del_pollset_or_pollset_set_alternative(
+              exec_ctx, p->base.interested_parties, pp->pollset,
+              pp->pollset_set_alternative);
           grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, true, NULL);
           gpr_free(pp);
         }
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index c5a0a398b4..90948efa55 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -225,6 +225,7 @@ CORE_SOURCE_FILES = [
   'third_party/nanopb/pb_common.c',
   'third_party/nanopb/pb_decode.c',
   'third_party/nanopb/pb_encode.c',
+  'src/core/ext/lb_policy/common.c',
   'src/core/ext/lb_policy/pick_first/pick_first.c',
   'src/core/ext/lb_policy/round_robin/round_robin.c',
   'src/core/ext/resolver/dns/native/dns_resolver.c',