+++ /dev/null
-/* LibMemcached
- * Copyright (C) 2006-2009 Brian Aker
- * All rights reserved.
- *
- * Use and distribution licensed under the BSD license. See
- * the COPYING file in the parent directory for full text.
- *
- * Summary: Server IO, Not public!
- *
- */
-
-
-#include "common.h"
-#include "memcached_io.h"
-#include <sys/select.h>
-#include <poll.h>
-
-typedef enum {
- MEM_READ,
- MEM_WRITE
-} memc_read_or_write;
-
-static ssize_t io_flush(memcached_server_st *ptr, memcached_return_t *error);
-static void increment_udp_message_id(memcached_server_st *ptr);
-
-static memcached_return_t io_wait(memcached_server_st *ptr,
- memc_read_or_write read_or_write)
-{
- struct pollfd fds= {
- .fd= ptr->fd,
- .events = POLLIN
- };
- int error;
-
- unlikely (read_or_write == MEM_WRITE) /* write */
- fds.events= POLLOUT;
-
- /*
- ** We are going to block on write, but at least on Solaris we might block
- ** on write if we haven't read anything from our input buffer..
- ** Try to purge the input buffer if we don't do any flow control in the
- ** application layer (just sending a lot of data etc)
- ** The test is moved down in the purge function to avoid duplication of
- ** the test.
- */
- if (read_or_write == MEM_WRITE)
- {
- memcached_return_t rc= memcached_purge(ptr);
- if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
- return MEMCACHED_FAILURE;
- }
-
- int timeout= ptr->root->poll_timeout;
- if (ptr->root->flags.no_block == false)
- timeout= -1;
-
- error= poll(&fds, 1, timeout);
-
- if (error == 1)
- return MEMCACHED_SUCCESS;
- else if (error == 0)
- return MEMCACHED_TIMEOUT;
-
- /* Imposssible for anything other then -1 */
- WATCHPOINT_ASSERT(error == -1);
- memcached_quit_server(ptr, 1);
-
- return MEMCACHED_FAILURE;
-}
-
-/**
- * Try to fill the input buffer for a server with as much
- * data as possible.
- *
- * @param ptr the server to pack
- */
-static bool repack_input_buffer(memcached_server_st *ptr)
-{
- if (ptr->read_ptr != ptr->read_buffer)
- {
- /* Move all of the data to the beginning of the buffer so
- ** that we can fit more data into the buffer...
- */
- memmove(ptr->read_buffer, ptr->read_ptr, ptr->read_buffer_length);
- ptr->read_ptr= ptr->read_buffer;
- ptr->read_data_length= ptr->read_buffer_length;
- }
-
- /* There is room in the buffer, try to fill it! */
- if (ptr->read_buffer_length != MEMCACHED_MAX_BUFFER)
- {
- /* Just try a single read to grab what's available */
- ssize_t nr= read(ptr->fd,
- ptr->read_ptr + ptr->read_data_length,
- MEMCACHED_MAX_BUFFER - ptr->read_data_length);
-
- if (nr > 0)
- {
- ptr->read_data_length+= (size_t)nr;
- ptr->read_buffer_length+= (size_t)nr;
- return true;
- }
- }
- return false;
-}
-
-/**
- * If the we have callbacks connected to this server structure
- * we may start process the input queue and fire the callbacks
- * for the incomming messages. This function is _only_ called
- * when the input buffer is full, so that we _know_ that we have
- * at least _one_ message to process.
- *
- * @param ptr the server to star processing iput messages for
- * @return true if we processed anything, false otherwise
- */
-static bool process_input_buffer(memcached_server_st *ptr)
-{
- /*
- ** We might be able to process some of the response messages if we
- ** have a callback set up
- */
- if (ptr->root->callbacks != NULL && ptr->root->flags.use_udp == false)
- {
- /*
- * We might have responses... try to read them out and fire
- * callbacks
- */
- memcached_callback_st cb= *ptr->root->callbacks;
-
- char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
- memcached_return_t error;
- error= memcached_response(ptr, buffer, sizeof(buffer),
- &ptr->root->result);
- if (error == MEMCACHED_SUCCESS)
- {
- for (unsigned int x= 0; x < cb.number_of_callback; x++)
- {
- error= (*cb.callback[x])(ptr->root, &ptr->root->result, cb.context);
- if (error != MEMCACHED_SUCCESS)
- break;
- }
-
- /* @todo what should I do with the error message??? */
- }
- /* @todo what should I do with other error messages?? */
- return true;
- }
-
- return false;
-}
-
-#ifdef UNUSED
-void memcached_io_preread(memcached_st *ptr)
-{
- unsigned int x;
-
- return;
-
- for (x= 0; x < ptr->number_of_hosts; x++)
- {
- if (memcached_server_response_count(ptr, x) &&
- ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
- {
- size_t data_read;
-
- data_read= read(ptr->hosts[x].fd,
- ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
- MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length);
- if (data_read == -1)
- continue;
-
- ptr->hosts[x].read_buffer_length+= data_read;
- ptr->hosts[x].read_data_length+= data_read;
- }
- }
-}
-#endif
-
-memcached_return_t memcached_io_read(memcached_server_st *ptr,
- void *buffer, size_t length, ssize_t *nread)
-{
- char *buffer_ptr;
-
- buffer_ptr= buffer;
-
- while (length)
- {
- if (!ptr->read_buffer_length)
- {
- ssize_t data_read;
-
- while (1)
- {
- data_read= read(ptr->fd, ptr->read_buffer, MEMCACHED_MAX_BUFFER);
- if (data_read > 0)
- break;
- else if (data_read == -1)
- {
- ptr->cached_errno= errno;
- memcached_return_t rc= MEMCACHED_UNKNOWN_READ_FAILURE;
- switch (errno)
- {
- case EAGAIN:
- case EINTR:
- if ((rc= io_wait(ptr, MEM_READ)) == MEMCACHED_SUCCESS)
- continue;
- /* fall through */
-
- default:
- {
- memcached_quit_server(ptr, 1);
- *nread= -1;
- return rc;
- }
- }
- }
- else
- {
- /*
- EOF. Any data received so far is incomplete
- so discard it. This always reads by byte in case of TCP
- and protocol enforcement happens at memcached_response()
- looking for '\n'. We do not care for UDB which requests 8 bytes
- at once. Generally, this means that connection went away. Since
- for blocking I/O we do not return 0 and for non-blocking case
- it will return EGAIN if data is not immediatly available.
- */
- memcached_quit_server(ptr, 1);
- *nread= -1;
- return MEMCACHED_UNKNOWN_READ_FAILURE;
- }
- }
-
- ptr->io_bytes_sent = 0;
- ptr->read_data_length= (size_t) data_read;
- ptr->read_buffer_length= (size_t) data_read;
- ptr->read_ptr= ptr->read_buffer;
- }
-
- if (length > 1)
- {
- size_t difference;
-
- difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
-
- memcpy(buffer_ptr, ptr->read_ptr, difference);
- length -= difference;
- ptr->read_ptr+= difference;
- ptr->read_buffer_length-= difference;
- buffer_ptr+= difference;
- }
- else
- {
- *buffer_ptr= *ptr->read_ptr;
- ptr->read_ptr++;
- ptr->read_buffer_length--;
- buffer_ptr++;
- break;
- }
- }
-
- ptr->server_failure_counter= 0;
- *nread = (ssize_t)(buffer_ptr - (char*)buffer);
- return MEMCACHED_SUCCESS;
-}
-
-ssize_t memcached_io_write(memcached_server_st *ptr,
- const void *buffer, size_t length, char with_flush)
-{
- size_t original_length;
- const char* buffer_ptr;
-
- WATCHPOINT_ASSERT(ptr->fd != -1);
-
- original_length= length;
- buffer_ptr= buffer;
-
- while (length)
- {
- char *write_ptr;
- size_t should_write;
- size_t buffer_end;
-
- if (ptr->type == MEMCACHED_CONNECTION_UDP)
- {
- //UDP does not support partial writes
- buffer_end= MAX_UDP_DATAGRAM_LENGTH;
- should_write= length;
- if (ptr->write_buffer_offset + should_write > buffer_end)
- return -1;
- }
- else
- {
- buffer_end= MEMCACHED_MAX_BUFFER;
- should_write= buffer_end - ptr->write_buffer_offset;
- should_write= (should_write < length) ? should_write : length;
- }
-
- write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
- memcpy(write_ptr, buffer_ptr, should_write);
- ptr->write_buffer_offset+= should_write;
- buffer_ptr+= should_write;
- length-= should_write;
-
- if (ptr->write_buffer_offset == buffer_end && ptr->type != MEMCACHED_CONNECTION_UDP)
- {
- memcached_return_t rc;
- ssize_t sent_length;
-
- WATCHPOINT_ASSERT(ptr->fd != -1);
- sent_length= io_flush(ptr, &rc);
- if (sent_length == -1)
- return -1;
-
- /* If io_flush calls memcached_purge, sent_length may be 0 */
- unlikely (sent_length != 0)
- {
- WATCHPOINT_ASSERT(sent_length == (ssize_t)buffer_end);
- }
- }
- }
-
- if (with_flush)
- {
- memcached_return_t rc;
- WATCHPOINT_ASSERT(ptr->fd != -1);
- if (io_flush(ptr, &rc) == -1)
- return -1;
- }
-
- return (ssize_t) original_length;
-}
-
-memcached_return_t memcached_io_close(memcached_server_st *ptr)
-{
- int r;
-
- if (ptr->fd == -1)
- return MEMCACHED_SUCCESS;
-
- /* in case of death shutdown to avoid blocking at close() */
- if (1)
- {
- r= shutdown(ptr->fd, SHUT_RDWR);
-
-#ifdef DEBUG
- if (r && errno != ENOTCONN)
- {
- WATCHPOINT_NUMBER(ptr->fd);
- WATCHPOINT_ERRNO(errno);
- WATCHPOINT_ASSERT(errno);
- }
-#endif
- }
-
- r= close(ptr->fd);
-#ifdef DEBUG
- if (r != 0)
- WATCHPOINT_ERRNO(errno);
-#endif
-
- return MEMCACHED_SUCCESS;
-}
-
-memcached_server_st *memcached_io_get_readable_server(memcached_st *memc)
-{
-#define MAX_SERVERS_TO_POLL 100
- struct pollfd fds[MAX_SERVERS_TO_POLL];
- unsigned int host_index= 0;
-
- for (unsigned int x= 0;
- x< memc->number_of_hosts && host_index < MAX_SERVERS_TO_POLL;
- ++x)
- {
- if (memc->hosts[x].read_buffer_length > 0) /* I have data in the buffer */
- return &memc->hosts[x];
-
- if (memcached_server_response_count(&memc->hosts[x]) > 0)
- {
- fds[host_index].events = POLLIN;
- fds[host_index].revents = 0;
- fds[host_index].fd = memc->hosts[x].fd;
- ++host_index;
- }
- }
-
- if (host_index < 2)
- {
- /* We have 0 or 1 server with pending events.. */
- for (unsigned int x= 0; x< memc->number_of_hosts; ++x)
- if (memcached_server_response_count(&memc->hosts[x]) > 0)
- return &memc->hosts[x];
-
- return NULL;
- }
-
- int err= poll(fds, host_index, memc->poll_timeout);
- switch (err) {
- case -1:
- memc->cached_errno = errno;
- /* FALLTHROUGH */
- case 0:
- break;
- default:
- for (unsigned int x= 0; x < host_index; ++x)
- if (fds[x].revents & POLLIN)
- for (unsigned int y= 0; y < memc->number_of_hosts; ++y)
- if (memc->hosts[y].fd == fds[x].fd)
- return &memc->hosts[y];
- }
-
- return NULL;
-}
-
-static ssize_t io_flush(memcached_server_st *ptr,
- memcached_return_t *error)
-{
- /*
- ** We might want to purge the input buffer if we haven't consumed
- ** any output yet... The test for the limits is the purge is inline
- ** in the purge function to avoid duplicating the logic..
- */
- {
- memcached_return_t rc;
- WATCHPOINT_ASSERT(ptr->fd != -1);
- rc= memcached_purge(ptr);
-
- if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
- return -1;
- }
- ssize_t sent_length;
- size_t return_length;
- char *local_write_ptr= ptr->write_buffer;
- size_t write_length= ptr->write_buffer_offset;
-
- *error= MEMCACHED_SUCCESS;
-
- WATCHPOINT_ASSERT(ptr->fd != -1);
-
- // UDP Sanity check, make sure that we are not sending somthing too big
- if (ptr->type == MEMCACHED_CONNECTION_UDP && write_length > MAX_UDP_DATAGRAM_LENGTH)
- return -1;
-
- if (ptr->write_buffer_offset == 0 || (ptr->type == MEMCACHED_CONNECTION_UDP
- && ptr->write_buffer_offset == UDP_DATAGRAM_HEADER_LENGTH))
- return 0;
-
- /* Looking for memory overflows */
-#if defined(DEBUG)
- if (write_length == MEMCACHED_MAX_BUFFER)
- WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
- WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
-#endif
-
- return_length= 0;
- while (write_length)
- {
- WATCHPOINT_ASSERT(ptr->fd != -1);
- WATCHPOINT_ASSERT(write_length > 0);
- sent_length= 0;
- if (ptr->type == MEMCACHED_CONNECTION_UDP)
- increment_udp_message_id(ptr);
- sent_length= write(ptr->fd, local_write_ptr, write_length);
-
- if (sent_length == -1)
- {
- ptr->cached_errno= errno;
- switch (errno)
- {
- case ENOBUFS:
- continue;
- case EAGAIN:
- {
- /*
- * We may be blocked on write because the input buffer
- * is full. Let's check if we have room in our input
- * buffer for more data and retry the write before
- * waiting..
- */
- if (repack_input_buffer(ptr) ||
- process_input_buffer(ptr))
- continue;
-
- memcached_return_t rc;
- rc= io_wait(ptr, MEM_WRITE);
-
- if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_TIMEOUT)
- continue;
-
- memcached_quit_server(ptr, 1);
- return -1;
- }
- default:
- memcached_quit_server(ptr, 1);
- *error= MEMCACHED_ERRNO;
- return -1;
- }
- }
-
- if (ptr->type == MEMCACHED_CONNECTION_UDP &&
- (size_t)sent_length != write_length)
- {
- memcached_quit_server(ptr, 1);
- return -1;
- }
-
- ptr->io_bytes_sent += (uint32_t) sent_length;
-
- local_write_ptr+= sent_length;
- write_length-= (uint32_t) sent_length;
- return_length+= (uint32_t) sent_length;
- }
-
- WATCHPOINT_ASSERT(write_length == 0);
- // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
- // ptr->write_buffer_offset);
-
- // if we are a udp server, the begining of the buffer is reserverd for
- // the upd frame header
- if (ptr->type == MEMCACHED_CONNECTION_UDP)
- ptr->write_buffer_offset= UDP_DATAGRAM_HEADER_LENGTH;
- else
- ptr->write_buffer_offset= 0;
-
- return (ssize_t) return_length;
-}
-
-/*
- Eventually we will just kill off the server with the problem.
-*/
-void memcached_io_reset(memcached_server_st *ptr)
-{
- memcached_quit_server(ptr, 1);
-}
-
-/**
- * Read a given number of bytes from the server and place it into a specific
- * buffer. Reset the IO channel on this server if an error occurs.
- */
-memcached_return_t memcached_safe_read(memcached_server_st *ptr,
- void *dta,
- size_t size)
-{
- size_t offset= 0;
- char *data= dta;
-
- while (offset < size)
- {
- ssize_t nread;
- memcached_return_t rc= memcached_io_read(ptr, data + offset, size - offset,
- &nread);
- if (rc != MEMCACHED_SUCCESS)
- return rc;
-
- offset+= (size_t) nread;
- }
-
- return MEMCACHED_SUCCESS;
-}
-
-memcached_return_t memcached_io_readline(memcached_server_st *ptr,
- char *buffer_ptr,
- size_t size)
-{
- bool line_complete= false;
- size_t total_nr= 0;
-
- while (!line_complete)
- {
- if (ptr->read_buffer_length == 0)
- {
- /*
- * We don't have any data in the buffer, so let's fill the read
- * buffer. Call the standard read function to avoid duplicating
- * the logic.
- */
- ssize_t nread;
- memcached_return_t rc= memcached_io_read(ptr, buffer_ptr, 1, &nread);
- if (rc != MEMCACHED_SUCCESS)
- return rc;
-
- if (*buffer_ptr == '\n')
- line_complete= true;
-
- ++buffer_ptr;
- ++total_nr;
- }
-
- /* Now let's look in the buffer and copy as we go! */
- while (ptr->read_buffer_length && total_nr < size && !line_complete)
- {
- *buffer_ptr = *ptr->read_ptr;
- if (*buffer_ptr == '\n')
- line_complete = true;
- --ptr->read_buffer_length;
- ++ptr->read_ptr;
- ++total_nr;
- ++buffer_ptr;
- }
-
- if (total_nr == size)
- return MEMCACHED_PROTOCOL_ERROR;
- }
-
- return MEMCACHED_SUCCESS;
-}
-
-/*
- * The udp request id consists of two seperate sections
- * 1) The thread id
- * 2) The message number
- * The thread id should only be set when the memcached_st struct is created
- * and should not be changed.
- *
- * The message num is incremented for each new message we send, this function
- * extracts the message number from message_id, increments it and then
- * writes the new value back into the header
- */
-static void increment_udp_message_id(memcached_server_st *ptr)
-{
- struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
- uint16_t cur_req= get_udp_datagram_request_id(header);
- int msg_num= get_msg_num_from_request_id(cur_req);
- int thread_id= get_thread_id_from_request_id(cur_req);
-
- if (((++msg_num) & UDP_REQUEST_ID_THREAD_MASK) != 0)
- msg_num= 0;
-
- header->request_id= htons((uint16_t) (thread_id | msg_num));
-}
-
-memcached_return_t memcached_io_init_udp_header(memcached_server_st *ptr, uint16_t thread_id)
-{
- if (thread_id > UDP_REQUEST_ID_MAX_THREAD_ID)
- return MEMCACHED_FAILURE;
-
- struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
- header->request_id= htons((uint16_t) (generate_udp_request_thread_id(thread_id)));
- header->num_datagrams= htons(1);
- header->sequence_number= htons(0);
-
- return MEMCACHED_SUCCESS;
-}
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