post-merge

1 files changed, 262 insertions, 180 deletions

diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 4dc51bf031..7b3e412db0 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -36,22 +36,22 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
 #include "src/core/channel/census_filter.h"
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/connected_channel.h"
 #include "src/core/iomgr/iomgr.h"
+#include "src/core/support/stack_lockfree.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/call.h"
 #include "src/core/surface/channel.h"
 #include "src/core/surface/completion_queue.h"
 #include "src/core/surface/init.h"
 #include "src/core/transport/metadata.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/useful.h>
-
-typedef enum { PENDING_START, CALL_LIST_COUNT } call_list;
 
 typedef struct listener {
   void *arg;
@@ -74,8 +74,8 @@ typedef enum { BATCH_CALL, REGISTERED_CALL } requested_call_type;
 
 typedef struct requested_call {
   requested_call_type type;
-  struct requested_call *next;
   void *tag;
+  grpc_server *server;
   grpc_completion_queue *cq_bound_to_call;
   grpc_completion_queue *cq_for_notification;
   grpc_call **call;
@@ -94,14 +94,6 @@ typedef struct requested_call {
   } data;
 } requested_call;
 
-struct registered_method {
-  char *method;
-  char *host;
-  call_data *pending;
-  requested_call *requests;
-  registered_method *next;
-};
-
 typedef struct channel_registered_method {
   registered_method *server_registered_method;
   grpc_mdstr *method;
@@ -130,44 +122,6 @@ typedef struct shutdown_tag {
   grpc_cq_completion completion;
 } shutdown_tag;
 
-struct grpc_server {
-  size_t channel_filter_count;
-  const grpc_channel_filter **channel_filters;
-  grpc_channel_args *channel_args;
-
-  grpc_completion_queue **cqs;
-  grpc_pollset **pollsets;
-  size_t cq_count;
-
-  /* The two following mutexes control access to server-state
-     mu_global controls access to non-call-related state (e.g., channel state)
-     mu_call controls access to call-related state (e.g., the call lists)
-
-     If they are ever required to be nested, you must lock mu_global
-     before mu_call. This is currently used in shutdown processing
-     (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
-  gpr_mu mu_global; /* mutex for server and channel state */
-  gpr_mu mu_call;   /* mutex for call-specific state */
-
-  registered_method *registered_methods;
-  requested_call *requests;
-
-  gpr_uint8 shutdown;
-  gpr_uint8 shutdown_published;
-  size_t num_shutdown_tags;
-  shutdown_tag *shutdown_tags;
-
-  call_data *lists[CALL_LIST_COUNT];
-  channel_data root_channel_data;
-
-  listener *listeners;
-  int listeners_destroyed;
-  gpr_refcount internal_refcount;
-
-  /** when did we print the last shutdown progress message */
-  gpr_timespec last_shutdown_message_time;
-};
-
 typedef enum {
   /* waiting for metadata */
   NOT_STARTED,
@@ -179,6 +133,8 @@ typedef enum {
   ZOMBIED
 } call_state;
 
+typedef struct request_matcher request_matcher;
+
 struct call_data {
   grpc_call *call;
 
@@ -201,8 +157,20 @@ struct call_data {
   grpc_iomgr_closure server_on_recv;
   grpc_iomgr_closure kill_zombie_closure;
 
-  call_data **root[CALL_LIST_COUNT];
-  call_link links[CALL_LIST_COUNT];
+  call_data *pending_next;
+};
+
+struct request_matcher {
+  call_data *pending_head;
+  call_data *pending_tail;
+  gpr_stack_lockfree *requests;
+};
+
+struct registered_method {
+  char *method;
+  char *host;
+  request_matcher request_matcher;
+  registered_method *next;
 };
 
 typedef struct {
@@ -210,6 +178,48 @@ typedef struct {
   size_t num_channels;
 } channel_broadcaster;
 
+struct grpc_server {
+  size_t channel_filter_count;
+  const grpc_channel_filter **channel_filters;
+  grpc_channel_args *channel_args;
+
+  grpc_completion_queue **cqs;
+  grpc_pollset **pollsets;
+  size_t cq_count;
+
+  /* The two following mutexes control access to server-state
+     mu_global controls access to non-call-related state (e.g., channel state)
+     mu_call controls access to call-related state (e.g., the call lists)
+
+     If they are ever required to be nested, you must lock mu_global
+     before mu_call. This is currently used in shutdown processing
+     (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
+  gpr_mu mu_global; /* mutex for server and channel state */
+  gpr_mu mu_call;   /* mutex for call-specific state */
+
+  registered_method *registered_methods;
+  request_matcher unregistered_request_matcher;
+  /** free list of available requested_calls indices */
+  gpr_stack_lockfree *request_freelist;
+  /** requested call backing data */
+  requested_call *requested_calls;
+  int max_requested_calls;
+
+  gpr_atm shutdown_flag;
+  gpr_uint8 shutdown_published;
+  size_t num_shutdown_tags;
+  shutdown_tag *shutdown_tags;
+
+  channel_data root_channel_data;
+
+  listener *listeners;
+  int listeners_destroyed;
+  gpr_refcount internal_refcount;
+
+  /** when did we print the last shutdown progress message */
+  gpr_timespec last_shutdown_message_time;
+};
+
 #define SERVER_FROM_CALL_ELEM(elem) \
   (((channel_data *)(elem)->channel_data)->server)
 
@@ -220,7 +230,9 @@ static void fail_call(grpc_server *server, requested_call *rc);
    hold mu_call */
 static void maybe_finish_shutdown(grpc_server *server);
 
-/* channel broadcaster */
+/*
+ * channel broadcaster
+ */
 
 /* assumes server locked */
 static void channel_broadcaster_init(grpc_server *s, channel_broadcaster *cb) {
@@ -281,55 +293,44 @@ static void channel_broadcaster_shutdown(channel_broadcaster *cb,
   gpr_free(cb->channels);
 }
 
-/* call list */
+/*
+ * request_matcher
+ */
+
+static void request_matcher_init(request_matcher *request_matcher,
+                                 int entries) {
+  memset(request_matcher, 0, sizeof(*request_matcher));
+  request_matcher->requests = gpr_stack_lockfree_create(entries);
+}
 
-static int call_list_join(call_data **root, call_data *call, call_list list) {
-  GPR_ASSERT(!call->root[list]);
-  call->root[list] = root;
-  if (!*root) {
-    *root = call;
-    call->links[list].next = call->links[list].prev = call;
-  } else {
-    call->links[list].next = *root;
-    call->links[list].prev = (*root)->links[list].prev;
-    call->links[list].next->links[list].prev =
-        call->links[list].prev->links[list].next = call;
-  }
-  return 1;
+static void request_matcher_destroy(request_matcher *request_matcher) {
+  GPR_ASSERT(gpr_stack_lockfree_pop(request_matcher->requests) == -1);
+  gpr_stack_lockfree_destroy(request_matcher->requests);
 }
 
-static call_data *call_list_remove_head(call_data **root, call_list list) {
-  call_data *out = *root;
-  if (out) {
-    out->root[list] = NULL;
-    if (out->links[list].next == out) {
-      *root = NULL;
-    } else {
-      *root = out->links[list].next;
-      out->links[list].next->links[list].prev = out->links[list].prev;
-      out->links[list].prev->links[list].next = out->links[list].next;
-    }
-  }
-  return out;
+static void kill_zombie(void *elem, int success) {
+  grpc_call_destroy(grpc_call_from_top_element(elem));
 }
 
-static int call_list_remove(call_data *call, call_list list) {
-  call_data **root = call->root[list];
-  if (root == NULL) return 0;
-  call->root[list] = NULL;
-  if (*root == call) {
-    *root = call->links[list].next;
-    if (*root == call) {
-      *root = NULL;
-      return 1;
-    }
+static void request_matcher_zombify_all_pending_calls(
+    request_matcher *request_matcher) {
+  while (request_matcher->pending_head) {
+    call_data *calld = request_matcher->pending_head;
+    request_matcher->pending_head = calld->pending_next;
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_iomgr_closure_init(
+        &calld->kill_zombie_closure, kill_zombie,
+        grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+    grpc_iomgr_add_callback(&calld->kill_zombie_closure);
   }
-  GPR_ASSERT(*root != call);
-  call->links[list].next->links[list].prev = call->links[list].prev;
-  call->links[list].prev->links[list].next = call->links[list].next;
-  return 1;
 }
 
+/*
+ * server proper
+ */
+
 static void server_ref(grpc_server *server) {
   gpr_ref(&server->internal_refcount);
 }
@@ -343,6 +344,7 @@ static void server_delete(grpc_server *server) {
   gpr_free(server->channel_filters);
   while ((rm = server->registered_methods) != NULL) {
     server->registered_methods = rm->next;
+    request_matcher_destroy(&rm->request_matcher);
     gpr_free(rm->method);
     gpr_free(rm->host);
     gpr_free(rm);
@@ -350,9 +352,12 @@ static void server_delete(grpc_server *server) {
   for (i = 0; i < server->cq_count; i++) {
     GRPC_CQ_INTERNAL_UNREF(server->cqs[i], "server");
   }
+  request_matcher_destroy(&server->unregistered_request_matcher);
+  gpr_stack_lockfree_destroy(server->request_freelist);
   gpr_free(server->cqs);
   gpr_free(server->pollsets);
   gpr_free(server->shutdown_tags);
+  gpr_free(server->requested_calls);
   gpr_free(server);
 }
 
@@ -391,25 +396,38 @@ static void destroy_channel(channel_data *chand) {
 }
 
 static void finish_start_new_rpc(grpc_server *server, grpc_call_element *elem,
-                                 call_data **pending_root,
-                                 requested_call **requests) {
-  requested_call *rc;
+                                 request_matcher *request_matcher) {
   call_data *calld = elem->call_data;
-  gpr_mu_lock(&server->mu_call);
-  rc = *requests;
-  if (rc == NULL) {
+  int request_id;
+
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_iomgr_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
+    grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+    return;
+  }
+
+  request_id = gpr_stack_lockfree_pop(request_matcher->requests);
+  if (request_id == -1) {
+    gpr_mu_lock(&server->mu_call);
     gpr_mu_lock(&calld->mu_state);
     calld->state = PENDING;
     gpr_mu_unlock(&calld->mu_state);
-    call_list_join(pending_root, calld, PENDING_START);
+    if (request_matcher->pending_head == NULL) {
+      request_matcher->pending_tail = request_matcher->pending_head = calld;
+    } else {
+      request_matcher->pending_tail->pending_next = calld;
+      request_matcher->pending_tail = calld;
+    }
+    calld->pending_next = NULL;
     gpr_mu_unlock(&server->mu_call);
   } else {
-    *requests = rc->next;
     gpr_mu_lock(&calld->mu_state);
     calld->state = ACTIVATED;
     gpr_mu_unlock(&calld->mu_state);
-    gpr_mu_unlock(&server->mu_call);
-    begin_call(server, calld, rc);
+    begin_call(server, calld, &server->requested_calls[request_id]);
   }
 }
 
@@ -431,8 +449,8 @@ static void start_new_rpc(grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != calld->host) continue;
       if (rm->method != calld->path) continue;
-      finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requests);
+      finish_start_new_rpc(server, elem,
+                           &rm->server_registered_method->request_matcher);
       return;
     }
     /* check for a wildcard method definition (no host set) */
@@ -443,17 +461,12 @@ static void start_new_rpc(grpc_call_element *elem) {
       if (!rm) break;
       if (rm->host != NULL) continue;
       if (rm->method != calld->path) continue;
-      finish_start_new_rpc(server, elem, &rm->server_registered_method->pending,
-                           &rm->server_registered_method->requests);
+      finish_start_new_rpc(server, elem,
+                           &rm->server_registered_method->request_matcher);
       return;
     }
   }
-  finish_start_new_rpc(server, elem, &server->lists[PENDING_START],
-                       &server->requests);
-}
-
-static void kill_zombie(void *elem, int success) {
-  grpc_call_destroy(grpc_call_from_top_element(elem));
+  finish_start_new_rpc(server, elem, &server->unregistered_request_matcher);
 }
 
 static int num_listeners(grpc_server *server) {
@@ -481,15 +494,15 @@ static int num_channels(grpc_server *server) {
 
 static void maybe_finish_shutdown(grpc_server *server) {
   size_t i;
-  if (!server->shutdown || server->shutdown_published) {
+  if (!gpr_atm_acq_load(&server->shutdown_flag) || server->shutdown_published) {
     return;
   }
 
   if (server->root_channel_data.next != &server->root_channel_data ||
       server->listeners_destroyed < num_listeners(server)) {
-    if (gpr_time_cmp(
-            gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), server->last_shutdown_message_time),
-            gpr_time_from_seconds(1)) >= 0) {
+    if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
+                                  server->last_shutdown_message_time),
+                     gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
       server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
       gpr_log(GPR_DEBUG,
               "Waiting for %d channels and %d/%d listeners to be destroyed"
@@ -526,7 +539,7 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
 static void server_on_recv(void *ptr, int success) {
   grpc_call_element *elem = ptr;
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
+  gpr_timespec op_deadline;
 
   if (success && !calld->got_initial_metadata) {
     size_t i;
@@ -536,7 +549,9 @@ static void server_on_recv(void *ptr, int success) {
       grpc_stream_op *op = &ops[i];
       if (op->type != GRPC_OP_METADATA) continue;
       grpc_metadata_batch_filter(&op->data.metadata, server_filter, elem);
-      if (0 != gpr_time_cmp(op->data.metadata.deadline, gpr_inf_future)) {
+      op_deadline = op->data.metadata.deadline;
+      if (0 !=
+          gpr_time_cmp(op_deadline, gpr_inf_future(op_deadline.clock_type))) {
         calld->deadline = op->data.metadata.deadline;
       }
       calld->got_initial_metadata = 1;
@@ -571,11 +586,8 @@ static void server_on_recv(void *ptr, int success) {
       } else if (calld->state == PENDING) {
         calld->state = ZOMBIED;
         gpr_mu_unlock(&calld->mu_state);
-        gpr_mu_lock(&chand->server->mu_call);
-        call_list_remove(calld, PENDING_START);
-        gpr_mu_unlock(&chand->server->mu_call);
-        grpc_iomgr_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
-        grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+        /* zombied call will be destroyed when it's removed from the pending
+           queue... later */
       } else {
         gpr_mu_unlock(&calld->mu_state);
       }
@@ -610,7 +622,7 @@ static void accept_stream(void *cd, grpc_transport *transport,
   channel_data *chand = cd;
   /* create a call */
   grpc_call_create(chand->channel, NULL, transport_server_data, NULL, 0,
-                   gpr_inf_future);
+                   gpr_inf_future(GPR_CLOCK_REALTIME));
 }
 
 static void channel_connectivity_changed(void *cd, int iomgr_status_ignored) {
@@ -638,7 +650,7 @@ static void init_call_elem(grpc_call_element *elem,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   memset(calld, 0, sizeof(call_data));
-  calld->deadline = gpr_inf_future;
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
   calld->call = grpc_call_from_top_element(elem);
   gpr_mu_init(&calld->mu_state);
 
@@ -653,11 +665,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
 
-  if (calld->state == PENDING) {
-    gpr_mu_lock(&chand->server->mu_call);
-    call_list_remove(elem->call_data, PENDING_START);
-    gpr_mu_unlock(&chand->server->mu_call);
-  }
+  GPR_ASSERT(calld->state != PENDING);
 
   if (calld->host) {
     GRPC_MDSTR_UNREF(calld->host);
@@ -725,6 +733,7 @@ static const grpc_channel_filter server_surface_filter = {
     sizeof(channel_data),
     init_channel_elem,
     destroy_channel_elem,
+    grpc_call_next_get_peer,
     "server",
 };
 
@@ -742,9 +751,9 @@ void grpc_server_register_completion_queue(grpc_server *server,
   server->cqs[n] = cq;
 }
 
-grpc_server *grpc_server_create_from_filters(grpc_channel_filter **filters,
-                                             size_t filter_count,
-                                             const grpc_channel_args *args) {
+grpc_server *grpc_server_create_from_filters(
+    const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *args) {
   size_t i;
   /* TODO(census): restore this once we finalize census filter etc.
      int census_enabled = grpc_channel_args_is_census_enabled(args); */
@@ -764,6 +773,18 @@ grpc_server *grpc_server_create_from_filters(grpc_channel_filter **filters,
   server->root_channel_data.next = server->root_channel_data.prev =
       &server->root_channel_data;
 
+  /* TODO(ctiller): expose a channel_arg for this */
+  server->max_requested_calls = 32768;
+  server->request_freelist =
+      gpr_stack_lockfree_create(server->max_requested_calls);
+  for (i = 0; i < (size_t)server->max_requested_calls; i++) {
+    gpr_stack_lockfree_push(server->request_freelist, i);
+  }
+  request_matcher_init(&server->unregistered_request_matcher,
+                       server->max_requested_calls);
+  server->requested_calls = gpr_malloc(server->max_requested_calls *
+                                       sizeof(*server->requested_calls));
+
   /* Server filter stack is:
 
      server_surface_filter - for making surface API calls
@@ -811,6 +832,7 @@ void *grpc_server_register_method(grpc_server *server, const char *method,
   }
   m = gpr_malloc(sizeof(registered_method));
   memset(m, 0, sizeof(*m));
+  request_matcher_init(&m->request_matcher, server->max_requested_calls);
   m->method = gpr_strdup(method);
   m->host = gpr_strdup(host);
   m->next = server->registered_methods;
@@ -868,8 +890,8 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
     grpc_transport_perform_op(transport, &op);
   }
 
-  channel =
-      grpc_channel_create_from_filters(filters, num_filters, args, mdctx, 0);
+  channel = grpc_channel_create_from_filters(NULL, filters, num_filters, args,
+                                             mdctx, 0);
   chand = (channel_data *)grpc_channel_stack_element(
               grpc_channel_get_channel_stack(channel), 0)
               ->channel_data;
@@ -926,13 +948,51 @@ void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
   grpc_transport_perform_op(transport, &op);
 }
 
+typedef struct {
+  requested_call **requests;
+  size_t count;
+  size_t capacity;
+} request_killer;
+
+static void request_killer_init(request_killer *rk) {
+  memset(rk, 0, sizeof(*rk));
+}
+
+static void request_killer_add(request_killer *rk, requested_call *rc) {
+  if (rk->capacity == rk->count) {
+    rk->capacity = GPR_MAX(8, rk->capacity * 2);
+    rk->requests =
+        gpr_realloc(rk->requests, rk->capacity * sizeof(*rk->requests));
+  }
+  rk->requests[rk->count++] = rc;
+}
+
+static void request_killer_add_request_matcher(request_killer *rk,
+                                               grpc_server *server,
+                                               request_matcher *rm) {
+  int request_id;
+  while ((request_id = gpr_stack_lockfree_pop(rm->requests)) != -1) {
+    request_killer_add(rk, &server->requested_calls[request_id]);
+  }
+}
+
+static void request_killer_run(request_killer *rk, grpc_server *server) {
+  size_t i;
+  for (i = 0; i < rk->count; i++) {
+    fail_call(server, rk->requests[i]);
+  }
+  gpr_free(rk->requests);
+}
+
 void grpc_server_shutdown_and_notify(grpc_server *server,
                                      grpc_completion_queue *cq, void *tag) {
   listener *l;
-  requested_call *requests = NULL;
   registered_method *rm;
   shutdown_tag *sdt;
   channel_broadcaster broadcaster;
+  request_killer reqkill;
+
+  GRPC_SERVER_LOG_SHUTDOWN(GPR_INFO, server, cq, tag);
 
   /* lock, and gather up some stuff to do */
   gpr_mu_lock(&server->mu_global);
@@ -943,7 +1003,7 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   sdt = &server->shutdown_tags[server->num_shutdown_tags++];
   sdt->tag = tag;
   sdt->cq = cq;
-  if (server->shutdown) {
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
     gpr_mu_unlock(&server->mu_global);
     return;
   }
@@ -951,31 +1011,26 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
 
   channel_broadcaster_init(server, &broadcaster);
+  request_killer_init(&reqkill);
 
   /* collect all unregistered then registered calls */
   gpr_mu_lock(&server->mu_call);
-  requests = server->requests;
-  server->requests = NULL;
+  request_killer_add_request_matcher(&reqkill, server,
+                                     &server->unregistered_request_matcher);
+  request_matcher_zombify_all_pending_calls(
+      &server->unregistered_request_matcher);
   for (rm = server->registered_methods; rm; rm = rm->next) {
-    while (rm->requests != NULL) {
-      requested_call *c = rm->requests;
-      rm->requests = c->next;
-      c->next = requests;
-      requests = c;
-    }
+    request_killer_add_request_matcher(&reqkill, server, &rm->request_matcher);
+    request_matcher_zombify_all_pending_calls(&rm->request_matcher);
   }
   gpr_mu_unlock(&server->mu_call);
 
-  server->shutdown = 1;
+  gpr_atm_rel_store(&server->shutdown_flag, 1);
   maybe_finish_shutdown(server);
   gpr_mu_unlock(&server->mu_global);
 
   /* terminate all the requested calls */
-  while (requests != NULL) {
-    requested_call *next = requests->next;
-    fail_call(server, requests);
-    requests = next;
-  }
+  request_killer_run(&reqkill, server);
 
   /* Shutdown listeners */
   for (l = server->listeners; l; l = l->next) {
@@ -1007,7 +1062,7 @@ void grpc_server_destroy(grpc_server *server) {
   listener *l;
 
   gpr_mu_lock(&server->mu_global);
-  GPR_ASSERT(server->shutdown || !server->listeners);
+  GPR_ASSERT(gpr_atm_acq_load(&server->shutdown_flag) || !server->listeners);
   GPR_ASSERT(server->listeners_destroyed == num_listeners(server));
 
   while (server->listeners) {
@@ -1037,39 +1092,55 @@ void grpc_server_add_listener(grpc_server *server, void *arg,
 static grpc_call_error queue_call_request(grpc_server *server,
                                           requested_call *rc) {
   call_data *calld = NULL;
-  requested_call **requests = NULL;
-  gpr_mu_lock(&server->mu_call);
-  if (server->shutdown) {
-    gpr_mu_unlock(&server->mu_call);
+  request_matcher *request_matcher = NULL;
+  int request_id;
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    fail_call(server, rc);
+    return GRPC_CALL_OK;
+  }
+  request_id = gpr_stack_lockfree_pop(server->request_freelist);
+  if (request_id == -1) {
+    /* out of request ids: just fail this one */
     fail_call(server, rc);
     return GRPC_CALL_OK;
   }
   switch (rc->type) {
     case BATCH_CALL:
-      calld =
-          call_list_remove_head(&server->lists[PENDING_START], PENDING_START);
-      requests = &server->requests;
+      request_matcher = &server->unregistered_request_matcher;
       break;
     case REGISTERED_CALL:
-      calld = call_list_remove_head(
-          &rc->data.registered.registered_method->pending, PENDING_START);
-      requests = &rc->data.registered.registered_method->requests;
+      request_matcher = &rc->data.registered.registered_method->request_matcher;
       break;
   }
-  if (calld != NULL) {
-    gpr_mu_unlock(&server->mu_call);
-    gpr_mu_lock(&calld->mu_state);
-    GPR_ASSERT(calld->state == PENDING);
-    calld->state = ACTIVATED;
-    gpr_mu_unlock(&calld->mu_state);
-    begin_call(server, calld, rc);
-    return GRPC_CALL_OK;
-  } else {
-    rc->next = *requests;
-    *requests = rc;
+  server->requested_calls[request_id] = *rc;
+  gpr_free(rc);
+  if (gpr_stack_lockfree_push(request_matcher->requests, request_id)) {
+    /* this was the first queued request: we need to lock and start
+       matching calls */
+    gpr_mu_lock(&server->mu_call);
+    while ((calld = request_matcher->pending_head) != NULL) {
+      request_id = gpr_stack_lockfree_pop(request_matcher->requests);
+      if (request_id == -1) break;
+      request_matcher->pending_head = calld->pending_next;
+      gpr_mu_unlock(&server->mu_call);
+      gpr_mu_lock(&calld->mu_state);
+      if (calld->state == ZOMBIED) {
+        gpr_mu_unlock(&calld->mu_state);
+        grpc_iomgr_closure_init(
+            &calld->kill_zombie_closure, kill_zombie,
+            grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+        grpc_iomgr_add_callback(&calld->kill_zombie_closure);
+      } else {
+        GPR_ASSERT(calld->state == PENDING);
+        calld->state = ACTIVATED;
+        gpr_mu_unlock(&calld->mu_state);
+        begin_call(server, calld, &server->requested_calls[request_id]);
+      }
+      gpr_mu_lock(&server->mu_call);
+    }
     gpr_mu_unlock(&server->mu_call);
-    return GRPC_CALL_OK;
   }
+  return GRPC_CALL_OK;
 }
 
 grpc_call_error grpc_server_request_call(
@@ -1087,6 +1158,7 @@ grpc_call_error grpc_server_request_call(
   }
   grpc_cq_begin_op(cq_for_notification);
   rc->type = BATCH_CALL;
+  rc->server = server;
   rc->tag = tag;
   rc->cq_bound_to_call = cq_bound_to_call;
   rc->cq_for_notification = cq_for_notification;
@@ -1109,6 +1181,7 @@ grpc_call_error grpc_server_request_registered_call(
   }
   grpc_cq_begin_op(cq_for_notification);
   rc->type = REGISTERED_CALL;
+  rc->server = server;
   rc->tag = tag;
   rc->cq_bound_to_call = cq_bound_to_call;
   rc->cq_for_notification = cq_for_notification;
@@ -1188,7 +1261,16 @@ static void begin_call(grpc_server *server, call_data *calld,
 }
 
 static void done_request_event(void *req, grpc_cq_completion *c) {
-  gpr_free(req);
+  requested_call *rc = req;
+  grpc_server *server = rc->server;
+
+  if (rc >= server->requested_calls &&
+      rc < server->requested_calls + server->max_requested_calls) {
+    gpr_stack_lockfree_push(server->request_freelist,
+                            rc - server->requested_calls);
+  } else {
+    gpr_free(req);
+  }
 }
 
 static void fail_call(grpc_server *server, requested_call *rc) {