Mercurial > hg > nginx
view src/core/ngx_buf.h @ 8045:aa28c802409f
Resolver: make TCP write timer event cancelable.
Similar to 70e65bf8dfd7, the change is made to ensure that the ability to
cancel resolver tasks is fully controlled by the caller. As mentioned in the
referenced commit, it is safe to make this timer cancelable because resolve
tasks can have their own timeouts that are not cancelable.
The scenario where this may become a problem is a periodic background resolve
task (not tied to a specific request or a client connection), which receives a
response with short TTL, large enough to warrant fallback to a TCP query.
With each event loop wakeup, we either have a previously set write timer
instance or schedule a new one. The non-cancelable write timer can delay or
block graceful shutdown of a worker even if the ngx_resolver_ctx_t->cancelable
flag is set by the API user, and there are no other tasks or connections.
We use the resolver API in this way to maintain the list of upstream server
addresses specified with the 'resolve' parameter, and there could be third-party
modules implementing similar logic.
author | Aleksei Bavshin <a.bavshin@f5.com> |
---|---|
date | Wed, 01 Jun 2022 20:17:23 -0700 |
parents | ec2e6893caaa |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_BUF_H_INCLUDED_ #define _NGX_BUF_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> typedef void * ngx_buf_tag_t; typedef struct ngx_buf_s ngx_buf_t; struct ngx_buf_s { u_char *pos; u_char *last; off_t file_pos; off_t file_last; u_char *start; /* start of buffer */ u_char *end; /* end of buffer */ ngx_buf_tag_t tag; ngx_file_t *file; ngx_buf_t *shadow; /* the buf's content could be changed */ unsigned temporary:1; /* * the buf's content is in a memory cache or in a read only memory * and must not be changed */ unsigned memory:1; /* the buf's content is mmap()ed and must not be changed */ unsigned mmap:1; unsigned recycled:1; unsigned in_file:1; unsigned flush:1; unsigned sync:1; unsigned last_buf:1; unsigned last_in_chain:1; unsigned last_shadow:1; unsigned temp_file:1; /* STUB */ int num; }; struct ngx_chain_s { ngx_buf_t *buf; ngx_chain_t *next; }; typedef struct { ngx_int_t num; size_t size; } ngx_bufs_t; typedef struct ngx_output_chain_ctx_s ngx_output_chain_ctx_t; typedef ngx_int_t (*ngx_output_chain_filter_pt)(void *ctx, ngx_chain_t *in); typedef void (*ngx_output_chain_aio_pt)(ngx_output_chain_ctx_t *ctx, ngx_file_t *file); struct ngx_output_chain_ctx_s { ngx_buf_t *buf; ngx_chain_t *in; ngx_chain_t *free; ngx_chain_t *busy; unsigned sendfile:1; unsigned directio:1; unsigned unaligned:1; unsigned need_in_memory:1; unsigned need_in_temp:1; unsigned aio:1; #if (NGX_HAVE_FILE_AIO || NGX_COMPAT) ngx_output_chain_aio_pt aio_handler; #endif #if (NGX_THREADS || NGX_COMPAT) ngx_int_t (*thread_handler)(ngx_thread_task_t *task, ngx_file_t *file); ngx_thread_task_t *thread_task; #endif off_t alignment; ngx_pool_t *pool; ngx_int_t allocated; ngx_bufs_t bufs; ngx_buf_tag_t tag; ngx_output_chain_filter_pt output_filter; void *filter_ctx; }; typedef struct { ngx_chain_t *out; ngx_chain_t **last; ngx_connection_t *connection; ngx_pool_t *pool; off_t limit; } ngx_chain_writer_ctx_t; #define NGX_CHAIN_ERROR (ngx_chain_t *) NGX_ERROR #define ngx_buf_in_memory(b) ((b)->temporary || (b)->memory || (b)->mmap) #define ngx_buf_in_memory_only(b) (ngx_buf_in_memory(b) && !(b)->in_file) #define ngx_buf_special(b) \ (((b)->flush || (b)->last_buf || (b)->sync) \ && !ngx_buf_in_memory(b) && !(b)->in_file) #define ngx_buf_sync_only(b) \ ((b)->sync && !ngx_buf_in_memory(b) \ && !(b)->in_file && !(b)->flush && !(b)->last_buf) #define ngx_buf_size(b) \ (ngx_buf_in_memory(b) ? (off_t) ((b)->last - (b)->pos): \ ((b)->file_last - (b)->file_pos)) ngx_buf_t *ngx_create_temp_buf(ngx_pool_t *pool, size_t size); ngx_chain_t *ngx_create_chain_of_bufs(ngx_pool_t *pool, ngx_bufs_t *bufs); #define ngx_alloc_buf(pool) ngx_palloc(pool, sizeof(ngx_buf_t)) #define ngx_calloc_buf(pool) ngx_pcalloc(pool, sizeof(ngx_buf_t)) ngx_chain_t *ngx_alloc_chain_link(ngx_pool_t *pool); #define ngx_free_chain(pool, cl) \ (cl)->next = (pool)->chain; \ (pool)->chain = (cl) ngx_int_t ngx_output_chain(ngx_output_chain_ctx_t *ctx, ngx_chain_t *in); ngx_int_t ngx_chain_writer(void *ctx, ngx_chain_t *in); ngx_int_t ngx_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain, ngx_chain_t *in); ngx_chain_t *ngx_chain_get_free_buf(ngx_pool_t *p, ngx_chain_t **free); void ngx_chain_update_chains(ngx_pool_t *p, ngx_chain_t **free, ngx_chain_t **busy, ngx_chain_t **out, ngx_buf_tag_t tag); off_t ngx_chain_coalesce_file(ngx_chain_t **in, off_t limit); ngx_chain_t *ngx_chain_update_sent(ngx_chain_t *in, off_t sent); #endif /* _NGX_BUF_H_INCLUDED_ */