/* 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"
typedef enum {
MEM_READ,
MEM_WRITE
} memc_read_or_write;
static ssize_t io_flush(memcached_server_write_instance_st ptr,
memcached_return_t *error);
static void increment_udp_message_id(memcached_server_write_instance_st ptr);
static memcached_return_t io_wait(memcached_server_write_instance_st ptr,
memc_read_or_write read_or_write)
{
struct pollfd fds= {
.fd= ptr->fd,
.events = POLLIN
};
int error;
if (read_or_write == MEM_WRITE) /* write */
{
fds.events= POLLOUT;
WATCHPOINT_SET(ptr->io_wait_count.write++);
}
else
{
WATCHPOINT_SET(ptr->io_wait_count.read++);
}
/*
** 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;
size_t loop_max= 5;
while (--loop_max) // While loop is for ERESTART or EINTR
{
error= poll(&fds, 1, timeout);
switch (error)
{
case 1: // Success!
WATCHPOINT_IF_LABELED_NUMBER(read_or_write && loop_max < 4, "read() times we had to loop, decremented down from 5", loop_max);
WATCHPOINT_IF_LABELED_NUMBER(!read_or_write && loop_max < 4, "write() times we had to loop, decremented down from 5", loop_max);
return MEMCACHED_SUCCESS;
case 0: // Timeout occured, we let the while() loop do its thing.
return MEMCACHED_TIMEOUT;
default:
WATCHPOINT_ERRNO(get_socket_errno());
switch (get_socket_errno())
{
#ifdef TARGET_OS_LINUX
case ERESTART:
#endif
case EINTR:
break;
default:
if (fds.revents & POLLERR)
{
int err;
socklen_t len= sizeof (err);
(void)getsockopt(ptr->fd, SOL_SOCKET, SO_ERROR, &err, &len);
ptr->cached_errno= (err == 0) ? get_socket_errno() : err;
}
else
{
ptr->cached_errno= get_socket_errno();
}
memcached_quit_server(ptr, true);
return MEMCACHED_FAILURE;
}
}
}
/* Imposssible for anything other then -1 */
WATCHPOINT_ASSERT(error == -1);
ptr->cached_errno= get_socket_errno();
memcached_quit_server(ptr, true);
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_write_instance_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= recv(ptr->fd,
ptr->read_ptr + ptr->read_data_length,
MEMCACHED_MAX_BUFFER - ptr->read_data_length,
0);
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_write_instance_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;
memcached_set_processing_input((memcached_st *)ptr->root, true);
char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
memcached_return_t error;
memcached_st *root= (memcached_st *)ptr->root;
error= memcached_response(ptr, buffer, sizeof(buffer),
&root->result);
memcached_set_processing_input(root, false);
if (error == MEMCACHED_SUCCESS)
{
for (unsigned int x= 0; x < cb.number_of_callback; x++)
{
error= (*cb.callback[x])(ptr->root, &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;
}
static inline void memcached_io_cork_push(memcached_server_st *ptr)
{
(void)ptr;
#ifdef CORK
if (ptr->root->flags.cork == false || ptr->state.is_corked)
return;
int enable= 1;
int err= setsockopt(ptr->fd, IPPROTO_TCP, CORK,
&enable, (socklen_t)sizeof(int));
if (! err)
ptr->state.is_corked= true;
WATCHPOINT_ASSERT(ptr->state.is_corked == true);
#endif
}
static inline void memcached_io_cork_pop(memcached_server_st *ptr)
{
(void)ptr;
#ifdef CORK
if (ptr->root->flags.cork == false || ptr->state.is_corked == false)
return;
int enable= 0;
int err= setsockopt(ptr->fd, IPPROTO_TCP, CORK,
&enable, (socklen_t)sizeof(int));
if (! err)
ptr->state.is_corked= false;
WATCHPOINT_ASSERT(ptr->state.is_corked == false);
#endif
}
#if 0 // Dead code, this should be removed.
void memcached_io_preread(memcached_st *ptr)
{
unsigned int x;
return;
for (x= 0; x < memcached_server_count(ptr); x++)
{
if (memcached_server_response_count(ptr, x) &&
ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
{
size_t data_read;
data_read= recv(ptr->hosts[x].fd,
ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length, 0);
if (data_read == SOCKET_ERROR)
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_write_instance_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= recv(ptr->fd, ptr->read_buffer, MEMCACHED_MAX_BUFFER, 0);
if (data_read > 0)
{
break;
}
else if (data_read == SOCKET_ERROR)
{
ptr->cached_errno= get_socket_errno();
memcached_return_t rc= MEMCACHED_ERRNO;
switch (get_socket_errno())
{
case EWOULDBLOCK:
#ifdef USE_EAGAIN
case EAGAIN:
#endif
case EINTR:
#ifdef TARGET_OS_LINUX
case ERESTART:
#endif
if ((rc= io_wait(ptr, MEM_READ)) == MEMCACHED_SUCCESS)
continue;
/* fall through */
default:
{
memcached_quit_server(ptr, true);
*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.
*/
WATCHPOINT_STRING("We had a zero length recv()");
memcached_quit_server(ptr, true);
*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;
}
static ssize_t _io_write(memcached_server_write_instance_st ptr,
const void *buffer, size_t length, bool with_flush)
{
size_t original_length;
const char* buffer_ptr;
WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
original_length= length;
buffer_ptr= buffer;
/* more writable data is coming if a flush isn't required, so delay send */
if (! with_flush)
{
memcached_io_cork_push(ptr);
}
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 != INVALID_SOCKET);
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 != INVALID_SOCKET);
if (io_flush(ptr, &rc) == -1)
{
return -1;
}
memcached_io_cork_pop(ptr);
}
return (ssize_t) original_length;
}
ssize_t memcached_io_write(memcached_server_write_instance_st ptr,
const void *buffer, size_t length, bool with_flush)
{
return _io_write(ptr, buffer, length, with_flush);
}
ssize_t memcached_io_writev(memcached_server_write_instance_st ptr,
const struct libmemcached_io_vector_st *vector,
size_t number_of, bool with_flush)
{
ssize_t total= 0;
for (size_t x= 0; x < number_of; x++, vector++)
{
ssize_t returnable;
if ((returnable= _io_write(ptr, vector->buffer, vector->length, false)) == -1)
{
return -1;
}
total+= returnable;
}
if (with_flush)
{
if (memcached_io_write(ptr, NULL, 0, true) == -1)
{
return -1;
}
}
return total;
}
memcached_return_t memcached_io_close(memcached_server_write_instance_st ptr)
{
if (ptr->fd == INVALID_SOCKET)
{
return MEMCACHED_SUCCESS;
}
/* in case of death shutdown to avoid blocking at close() */
if (shutdown(ptr->fd, SHUT_RDWR) == SOCKET_ERROR && get_socket_errno() != ENOTCONN)
{
WATCHPOINT_NUMBER(ptr->fd);
WATCHPOINT_ERRNO(get_socket_errno());
WATCHPOINT_ASSERT(get_socket_errno());
}
if (closesocket(ptr->fd) == SOCKET_ERROR)
{
WATCHPOINT_ERRNO(get_socket_errno());
}
return MEMCACHED_SUCCESS;
}
memcached_server_write_instance_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 (uint32_t x= 0;
x< memcached_server_count(memc) && host_index < MAX_SERVERS_TO_POLL;
++x)
{
memcached_server_write_instance_st instance=
memcached_server_instance_fetch(memc, x);
if (instance->read_buffer_length > 0) /* I have data in the buffer */
return instance;
if (memcached_server_response_count(instance) > 0)
{
fds[host_index].events = POLLIN;
fds[host_index].revents = 0;
fds[host_index].fd = instance->fd;
++host_index;
}
}
if (host_index < 2)
{
/* We have 0 or 1 server with pending events.. */
for (uint32_t x= 0; x< memcached_server_count(memc); ++x)
{
memcached_server_write_instance_st instance=
memcached_server_instance_fetch(memc, x);
if (memcached_server_response_count(instance) > 0)
{
return instance;
}
}
return NULL;
}
int err= poll(fds, host_index, memc->poll_timeout);
switch (err) {
case -1:
memc->cached_errno = get_socket_errno();
/* FALLTHROUGH */
case 0:
break;
default:
for (size_t x= 0; x < host_index; ++x)
{
if (fds[x].revents & POLLIN)
{
for (uint32_t y= 0; y < memcached_server_count(memc); ++y)
{
memcached_server_write_instance_st instance=
memcached_server_instance_fetch(memc, y);
if (instance->fd == fds[x].fd)
return instance;
}
}
}
}
return NULL;
}
static ssize_t io_flush(memcached_server_write_instance_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 != INVALID_SOCKET);
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 != INVALID_SOCKET);
// 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 != INVALID_SOCKET);
WATCHPOINT_ASSERT(write_length > 0);
sent_length= 0;
if (ptr->type == MEMCACHED_CONNECTION_UDP)
increment_udp_message_id(ptr);
sent_length= send(ptr->fd, local_write_ptr, write_length, 0);
if (sent_length == SOCKET_ERROR)
{
ptr->cached_errno= get_socket_errno();
#if 0 // @todo I should look at why we hit this bit of code hard frequently
WATCHPOINT_ERRNO(get_socket_errno());
WATCHPOINT_NUMBER(get_socket_errno());
#endif
switch (get_socket_errno())
{
case ENOBUFS:
continue;
case EWOULDBLOCK:
#ifdef USE_EAGAIN
case EAGAIN:
#endif
{
/*
* 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, true);
return -1;
}
default:
memcached_quit_server(ptr, true);
*error= MEMCACHED_ERRNO;
return -1;
}
}
if (ptr->type == MEMCACHED_CONNECTION_UDP &&
(size_t)sent_length != write_length)
{
memcached_quit_server(ptr, true);
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_write_instance_st ptr)
{
memcached_quit_server(ptr, true);
}
/**
* 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_write_instance_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_write_instance_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_write_instance_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_write_instance_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;
}