| /* |
| * |
| * 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 */ |