| /* |
| * |
| * Copyright 2016 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #ifndef GRPC_CORE_LIB_IOMGR_RESOURCE_QUOTA_H |
| #define GRPC_CORE_LIB_IOMGR_RESOURCE_QUOTA_H |
| |
| #include <grpc/grpc.h> |
| |
| #include "src/core/lib/debug/trace.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 grpc_core::TraceFlag grpc_resource_quota_trace; |
| |
| grpc_resource_quota* grpc_resource_quota_ref_internal( |
| grpc_resource_quota* resource_quota); |
| void grpc_resource_quota_unref_internal(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); |
| |
| /* Return a number indicating current memory pressure: |
| 0.0 ==> no memory usage |
| 1.0 ==> maximum memory usage */ |
| double grpc_resource_quota_get_memory_pressure( |
| grpc_resource_quota* resource_quota); |
| |
| size_t grpc_resource_quota_peek_size(grpc_resource_quota* resource_quota); |
| |
| typedef struct grpc_resource_user grpc_resource_user; |
| |
| grpc_resource_user* grpc_resource_user_create( |
| grpc_resource_quota* resource_quota, const char* name); |
| |
| /* Returns a borrowed reference to the underlying resource quota for this |
| resource user. */ |
| grpc_resource_quota* grpc_resource_user_quota( |
| grpc_resource_user* resource_user); |
| |
| void grpc_resource_user_ref(grpc_resource_user* resource_user); |
| void grpc_resource_user_unref(grpc_exec_ctx* exec_ctx, |
| grpc_resource_user* resource_user); |
| void grpc_resource_user_shutdown(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 */ |
| grpc_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, grpc_slice_buffer* dest); |
| |
| /* Allocate one slice of length \a size synchronously. */ |
| grpc_slice grpc_resource_user_slice_malloc(grpc_exec_ctx* exec_ctx, |
| grpc_resource_user* resource_user, |
| size_t size); |
| |
| #endif /* GRPC_CORE_LIB_IOMGR_RESOURCE_QUOTA_H */ |