Mercurial > hg > nginx
view src/os/win32/ngx_shmem.c @ 7583:efd71d49bde0
Events: available bytes calculation via ioctl(FIONREAD).
This makes it possible to avoid looping for a long time while working
with a fast enough peer when data are added to the socket buffer faster
than we are able to read and process them (ticket #1431). This is
basically what we already do on FreeBSD with kqueue, where information
about the number of bytes in the socket buffer is returned by
the kevent() call.
With other event methods rev->available is now set to -1 when the socket
is ready for reading. Later in ngx_recv() and ngx_recv_chain(), if
full buffer is received, real number of bytes in the socket buffer is
retrieved using ioctl(FIONREAD). Reading more than this number of bytes
ensures that even with edge-triggered event methods the event will be
triggered again, so it is safe to stop processing of the socket and
switch to other connections.
Using ioctl(FIONREAD) only after reading a full buffer is an optimization.
With this approach we only call ioctl(FIONREAD) when there are at least
two recv()/readv() calls.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 17 Oct 2019 16:02:19 +0300 |
parents | af7eba90645d |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> /* * Base addresses selected by system for shared memory mappings are likely * to be different on Windows Vista and later versions due to address space * layout randomization. This is however incompatible with storing absolute * addresses within the shared memory. * * To make it possible to store absolute addresses we create mappings * at the same address in all processes by starting mappings at predefined * addresses. The addresses were selected somewhat randomly in order to * minimize the probability that some other library doing something similar * conflicts with us. The addresses are from the following typically free * blocks: * * - 0x10000000 .. 0x70000000 (about 1.5 GB in total) on 32-bit platforms * - 0x000000007fff0000 .. 0x000007f68e8b0000 (about 8 TB) on 64-bit platforms * * Additionally, we allow to change the mapping address once it was detected * to be different from one originally used. This is needed to support * reconfiguration. */ #ifdef _WIN64 #define NGX_SHMEM_BASE 0x0000047047e00000 #else #define NGX_SHMEM_BASE 0x2efe0000 #endif ngx_uint_t ngx_allocation_granularity; ngx_int_t ngx_shm_alloc(ngx_shm_t *shm) { u_char *name; uint64_t size; static u_char *base = (u_char *) NGX_SHMEM_BASE; name = ngx_alloc(shm->name.len + 2 + NGX_INT32_LEN, shm->log); if (name == NULL) { return NGX_ERROR; } (void) ngx_sprintf(name, "%V_%s%Z", &shm->name, ngx_unique); ngx_set_errno(0); size = shm->size; shm->handle = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, (u_long) (size >> 32), (u_long) (size & 0xffffffff), (char *) name); if (shm->handle == NULL) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CreateFileMapping(%uz, %s) failed", shm->size, name); ngx_free(name); return NGX_ERROR; } ngx_free(name); if (ngx_errno == ERROR_ALREADY_EXISTS) { shm->exists = 1; } shm->addr = MapViewOfFileEx(shm->handle, FILE_MAP_WRITE, 0, 0, 0, base); if (shm->addr != NULL) { base += ngx_align(size, ngx_allocation_granularity); return NGX_OK; } ngx_log_debug3(NGX_LOG_DEBUG_CORE, shm->log, ngx_errno, "MapViewOfFileEx(%uz, %p) of file mapping \"%V\" failed, " "retry without a base address", shm->size, base, &shm->name); /* * Order of shared memory zones may be different in the master process * and worker processes after reconfiguration. As a result, the above * may fail due to a conflict with a previously created mapping remapped * to a different address. Additionally, there may be a conflict with * some other uses of the memory. In this case we retry without a base * address to let the system assign the address itself. */ shm->addr = MapViewOfFile(shm->handle, FILE_MAP_WRITE, 0, 0, 0); if (shm->addr != NULL) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "MapViewOfFile(%uz) of file mapping \"%V\" failed", shm->size, &shm->name); if (CloseHandle(shm->handle) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CloseHandle() of file mapping \"%V\" failed", &shm->name); } return NGX_ERROR; } ngx_int_t ngx_shm_remap(ngx_shm_t *shm, u_char *addr) { if (UnmapViewOfFile(shm->addr) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "UnmapViewOfFile(%p) of file mapping \"%V\" failed", shm->addr, &shm->name); return NGX_ERROR; } shm->addr = MapViewOfFileEx(shm->handle, FILE_MAP_WRITE, 0, 0, 0, addr); if (shm->addr != NULL) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "MapViewOfFileEx(%uz, %p) of file mapping \"%V\" failed", shm->size, addr, &shm->name); return NGX_ERROR; } void ngx_shm_free(ngx_shm_t *shm) { if (UnmapViewOfFile(shm->addr) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "UnmapViewOfFile(%p) of file mapping \"%V\" failed", shm->addr, &shm->name); } if (CloseHandle(shm->handle) == 0) { ngx_log_error(NGX_LOG_ALERT, shm->log, ngx_errno, "CloseHandle() of file mapping \"%V\" failed", &shm->name); } }