Merge remote-tracking branch 'upstream/master' into lb_policy_name_channel_arg

1 files changed, 224 insertions, 0 deletions

diff --git a/src/core/lib/iomgr/resource_quota.h b/src/core/lib/iomgr/resource_quota.h
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+/*
+ *
+ * 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_LIB_IOMGR_RESOURCE_QUOTA_H
+#define GRPC_CORE_LIB_IOMGR_RESOURCE_QUOTA_H
+
+#include <grpc/grpc.h>
+
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+/** \file Tracks resource usage against a pool.
+
+    The current implementation tracks only memory usage, but in the future
+    this may be extended to (for example) threads and file descriptors.
+
+    A grpc_resource_quota represents the pooled resources, and
+    grpc_resource_user instances attach to the quota and consume those
+    resources. They also offer a vector for reclamation: if we become
+    resource constrained, grpc_resource_user instances are asked (in turn) to
+    free up whatever they can so that the system as a whole can make progress.
+
+    There are three kinds of reclamation that take place, in order of increasing
+    invasiveness:
+    - an internal reclamation, where cached resource at the resource user level
+      is returned to the quota
+    - a benign reclamation phase, whereby resources that are in use but are not
+      helping anything make progress are reclaimed
+    - a destructive reclamation, whereby resources that are helping something
+      make progress may be enacted so that at least one part of the system can
+      complete.
+
+    Only one reclamation will be outstanding for a given quota at a given time.
+    On each reclamation attempt, the kinds of reclamation are tried in order of
+    increasing invasiveness, stopping at the first one that succeeds. Thus, on a
+    given reclamation attempt, if internal and benign reclamation both fail, it
+    will wind up doing a destructive reclamation. However, the next reclamation
+    attempt may then be able to get what it needs via internal or benign
+    reclamation, due to resources that may have been freed up by the destructive
+    reclamation in the previous attempt.
+
+    Future work will be to expose the current resource pressure so that back
+    pressure can be applied to avoid reclamation phases starting.
+
+    Resource users own references to resource quotas, and resource quotas
+    maintain lists of users (which users arrange to leave before they are
+    destroyed) */
+
+extern int grpc_resource_quota_trace;
+
+grpc_resource_quota *grpc_resource_quota_internal_ref(
+    grpc_resource_quota *resource_quota);
+void grpc_resource_quota_internal_unref(grpc_exec_ctx *exec_ctx,
+                                        grpc_resource_quota *resource_quota);
+grpc_resource_quota *grpc_resource_quota_from_channel_args(
+    const grpc_channel_args *channel_args);
+
+/* Resource users are kept in (potentially) several intrusive linked lists
+   at once. These are the list names. */
+typedef enum {
+  /* Resource users that are waiting for an allocation */
+  GRPC_RULIST_AWAITING_ALLOCATION,
+  /* Resource users that have free memory available for internal reclamation */
+  GRPC_RULIST_NON_EMPTY_FREE_POOL,
+  /* Resource users that have published a benign reclamation is available */
+  GRPC_RULIST_RECLAIMER_BENIGN,
+  /* Resource users that have published a destructive reclamation is
+     available */
+  GRPC_RULIST_RECLAIMER_DESTRUCTIVE,
+  /* Number of lists: must be last */
+  GRPC_RULIST_COUNT
+} grpc_rulist;
+
+typedef struct grpc_resource_user grpc_resource_user;
+
+/* Internal linked list pointers for a resource user */
+typedef struct {
+  grpc_resource_user *next;
+  grpc_resource_user *prev;
+} grpc_resource_user_link;
+
+struct grpc_resource_user {
+  /* The quota this resource user consumes from */
+  grpc_resource_quota *resource_quota;
+
+  /* Closure to schedule an allocation under the resource quota combiner lock */
+  grpc_closure allocate_closure;
+  /* Closure to publish a non empty free pool under the resource quota combiner
+     lock */
+  grpc_closure add_to_free_pool_closure;
+
+  gpr_mu mu;
+  /* Total allocated memory outstanding by this resource user in bytes;
+     always positive */
+  int64_t allocated;
+  /* The amount of memory (in bytes) this user has cached for its own use: to
+     avoid quota contention, each resource user can keep some memory in
+     addition to what it is immediately using (e.g., for caching), and the quota
+     can pull it back under memory pressure.
+     This value can become negative if more memory has been requested than
+     existed in the free pool, at which point the quota is consulted to bring
+     this value non-negative (asynchronously). */
+  int64_t free_pool;
+  /* A list of closures to call once free_pool becomes non-negative - ie when
+     all outstanding allocations have been granted. */
+  grpc_closure_list on_allocated;
+  /* True if we are currently trying to allocate from the quota, false if not */
+  bool allocating;
+  /* True if we are currently trying to add ourselves to the non-free quota
+     list, false otherwise */
+  bool added_to_free_pool;
+
+  /* Reclaimers: index 0 is the benign reclaimer, 1 is the destructive reclaimer
+   */
+  grpc_closure *reclaimers[2];
+  /* Trampoline closures to finish reclamation and re-enter the quota combiner
+     lock */
+  grpc_closure post_reclaimer_closure[2];
+
+  /* Closure to execute under the quota combiner to de-register and shutdown the
+     resource user */
+  grpc_closure destroy_closure;
+  /* User supplied closure to call once the user has finished shutting down AND
+     all outstanding allocations have been freed. Real type is grpc_closure*,
+     but it's stored as an atomic to avoid a mutex on some fast paths. */
+  gpr_atm on_done_destroy_closure;
+
+  /* Links in the various grpc_rulist lists */
+  grpc_resource_user_link links[GRPC_RULIST_COUNT];
+
+  /* The name of this resource user, for debugging/tracing */
+  char *name;
+};
+
+void grpc_resource_user_init(grpc_resource_user *resource_user,
+                             grpc_resource_quota *resource_quota,
+                             const char *name);
+void grpc_resource_user_shutdown(grpc_exec_ctx *exec_ctx,
+                                 grpc_resource_user *resource_user,
+                                 grpc_closure *on_done);
+void grpc_resource_user_destroy(grpc_exec_ctx *exec_ctx,
+                                grpc_resource_user *resource_user);
+
+/* Allocate from the resource user (and its quota).
+   If optional_on_done is NULL, then allocate immediately. This may push the
+   quota over-limit, at which point reclamation will kick in.
+   If optional_on_done is non-NULL, it will be scheduled when the allocation has
+   been granted by the quota. */
+void grpc_resource_user_alloc(grpc_exec_ctx *exec_ctx,
+                              grpc_resource_user *resource_user, size_t size,
+                              grpc_closure *optional_on_done);
+/* Release memory back to the quota */
+void grpc_resource_user_free(grpc_exec_ctx *exec_ctx,
+                             grpc_resource_user *resource_user, size_t size);
+/* Post a memory reclaimer to the resource user. Only one benign and one
+   destructive reclaimer can be posted at once. When executed, the reclaimer
+   MUST call grpc_resource_user_finish_reclamation before it completes, to
+   return control to the resource quota. */
+void grpc_resource_user_post_reclaimer(grpc_exec_ctx *exec_ctx,
+                                       grpc_resource_user *resource_user,
+                                       bool destructive, grpc_closure *closure);
+/* Finish a reclamation step */
+void grpc_resource_user_finish_reclamation(grpc_exec_ctx *exec_ctx,
+                                           grpc_resource_user *resource_user);
+
+/* Helper to allocate slices from a resource user */
+typedef struct grpc_resource_user_slice_allocator {
+  /* Closure for when a resource user allocation completes */
+  grpc_closure on_allocated;
+  /* Closure to call when slices have been allocated */
+  grpc_closure on_done;
+  /* Length of slices to allocate on the current request */
+  size_t length;
+  /* Number of slices to allocate on the current request */
+  size_t count;
+  /* Destination for slices to allocate on the current request */
+  gpr_slice_buffer *dest;
+  /* Parent resource user */
+  grpc_resource_user *resource_user;
+} grpc_resource_user_slice_allocator;
+
+/* Initialize a slice allocator.
+   When an allocation is completed, calls \a cb with arg \p. */
+void grpc_resource_user_slice_allocator_init(
+    grpc_resource_user_slice_allocator *slice_allocator,
+    grpc_resource_user *resource_user, grpc_iomgr_cb_func cb, void *p);
+
+/* Allocate \a count slices of length \a length into \a dest. Only one request
+   can be outstanding at a time. */
+void grpc_resource_user_alloc_slices(
+    grpc_exec_ctx *exec_ctx,
+    grpc_resource_user_slice_allocator *slice_allocator, size_t length,
+    size_t count, gpr_slice_buffer *dest);
+
+#endif /* GRPC_CORE_LIB_IOMGR_RESOURCE_QUOTA_H */