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EagerConnection.cpp
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EagerConnection.cpp
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#include "EagerConnection.h"
#include "IStatStore.h"
#include "Logs.h"
#include "istat/strfunc.h"
#include "threadfunc.h"
#include <istat/istattime.h>
#include <boost/thread.hpp>
#include <boost/bind/bind.hpp>
#include <boost/make_shared.hpp>
#include <iostream>
using namespace istat;
using boost::asio::ip::tcp;
using namespace boost::asio;
// Allow this to be manipulated later.
size_t maxBufferSize = 512*1024;
struct EagerConnectionEnabler : public EagerConnection {
EagerConnectionEnabler(boost::asio::io_service &svc) : EagerConnection(svc) {}
};
boost::shared_ptr<ConnectionInfo> EagerConnection::create(boost::asio::io_service &svc)
{
return boost::make_shared<EagerConnectionEnabler>(boost::ref(svc));
}
EagerConnection::EagerConnection(boost::asio::io_service &svc) :
tryingLater_(false),
tryLaterTime_(0),
backoff_(1),
successfulWritesDuringBackoff_(1),
interlock_(0),
socket_(svc),
resolver_(svc),
timer_(svc),
#if BOOST_VERSION >= 106700
strand_(svc.get_executor())
#else
strand_(svc)
#endif
{
init();
++IStatCounter::eagerconns_;
}
void EagerConnection::init()
{
opened_ = false;
backoff_ = 1;
successfulWritesDuringBackoff_ = 1;
writePending_ = false;
readPending_ = false;
}
EagerConnection::~EagerConnection()
{
close();
--IStatCounter::eagerconns_;
}
void EagerConnection::open() // called when accepted
{
LogSpam << "EagerConnection::open()";
std::stringstream ss;
ss << endpoint_;
endpointName_ = ss.str();
opened_ = true;
}
void EagerConnection::open(std::string const &dest, std::string const &initialData)
{
LogSpam << "EagerConnection::open(" << dest << ")";
close();
std::string host;
std::string port;
if (split(dest, ':', host, port) != 2)
{
throw std::runtime_error("open() destination must be host:port");
}
backoff_ = 1;
successfulWritesDuringBackoff_ = 1;
opened_ = true;
if (initialData.size())
{
initialData_ = initialData;
}
resolveHost_ = host;
resolvePort_ = port;
startResolve();
}
void EagerConnection::close()
{
LogSpam << "EagerConnection::close()";
if (!opened_)
{
return;
}
opened_ = false;
socket_.close();
timer_.cancel();
grab aholdof(mutex_);
writeBuf_.clear();
inBuf_.clear();
outgoing_.clear();
incoming_.clear();
disconnect_all_slots(onConnect_);
disconnect_all_slots(onDisconnect_);
disconnect_all_slots(onData_);
disconnect_all_slots(onWrite_);
}
bool EagerConnection::opened()
{
return opened_;
}
bool EagerConnection::connected()
{
return socket_.is_open();
}
size_t EagerConnection::pendingOut()
{
// vector may be implemented as "start" and "end" pointers
// which are not synchronously updated, and thus we could get
// a wrong size if reading while someone else is mutating.
// There's a separate race where the size may change after
// this function returns -- the lock doesn't solve that.
grab aholdof(mutex_);
return outgoing_.size();
}
size_t EagerConnection::pendingIn()
{
// vector may be implemented as "start" and "end" pointers
// which are not synchronously updated, and thus we could get
// a wrong size if reading while someone else is mutating.
// There's a separate race where the size may change after
// this function returns -- the lock doesn't solve that.
grab aholdof(mutex_);
return incoming_.size();
}
size_t EagerConnection::readIn(void *ptr, size_t maxSize)
{
LogSpam << "EagerConnection::readIn(" << maxSize << ")";
grab aholdof(mutex_);
size_t n = peekIn(ptr, maxSize);
consume(n);
return n;
}
size_t EagerConnection::peekIn(void *ptr, size_t maxSize)
{
LogSpam << "EagerConnection::peekIn(" << maxSize << ")";
grab aholdof(mutex_);
size_t n = maxSize;
if (n > incoming_.size())
{
n = incoming_.size();
}
if (n > 0 && ptr != 0)
{
memcpy(ptr, &incoming_[0], n);
}
return n;
}
void EagerConnection::consume(size_t n)
{
LogSpam << "EagerConnection::consume(" << n << ")";
if (!opened_)
{
return;
}
grab aholdof(mutex_);
if (n > 0)
{
assert(n <= incoming_.size());
if (n > incoming_.size())
{
throw std::runtime_error("EagerConnection::consume() of too much data");
}
incoming_.erase(incoming_.begin(), incoming_.begin() + n);
}
}
size_t EagerConnection::writeOut(std::string const &str)
{
return writeOut(str.c_str(), str.size());
}
size_t EagerConnection::writeOut(void const *data, size_t size)
{
LogSpam << "EagerConnection::writeOut(" << size << ")";
if (!opened_)
{
throw std::runtime_error("Attempt to writeOut() to a non-open() EagerConnection.");
}
grab aholdof(mutex_);
if (outgoing_.size() > maxBufferSize)
{
bool found = false;
LogDebug << "notice: pruning pending outgoing buffer";
// find a line somewhere in the middle, and cut at that point
for (std::vector<char>::iterator ptr(outgoing_.begin() + maxBufferSize/2),
end(outgoing_.end()); ptr != end; ++ptr)
{
if (*ptr == 10)
{
outgoing_.erase(outgoing_.begin(), ++ptr);
found = true;
break;
}
}
if (!found)
{
// toss it all, if there's no newline!
LogWarning << "error: there's no newline in the existing buffer data!";
outgoing_.clear();
}
}
outgoing_.insert(outgoing_.end(), (char const *)data, (char const *)data + size);
startWrite();
return outgoing_.size();
}
void EagerConnection::abort()
{
LogSpam << "EagerConnection::abort()";
socket_.close();
{
grab aholdof(mutex_);
writeBuf_.clear();
inBuf_.clear();
outgoing_.clear();
incoming_.clear();
}
onDisconnect_();
}
tcp::endpoint EagerConnection::endpoint() const
{
return endpoint_;
}
void EagerConnection::startResolve()
{
LogSpam << "EagerConnection::startResolve()";
time_t nowTime;
istat::istattime(&nowTime);
if (nowTime - tryLaterTime_ < backoff_ / 2)
{
LogError << "tryLater fired early: tryLaterTime" << tryLaterTime_ << "; nowTime" << nowTime << "; backoff" << backoff_ << "; forcing sleep.";
// force the thing to not suck down the CPU!
boost::this_thread::sleep(boost::posix_time::seconds(1));
}
LogNotice << "Resolving " << resolveHost_ << ":" << resolvePort_;
boost::system::error_code error;
tcp::resolver::iterator iter = resolver_.resolve(tcp::resolver::query(resolveHost_, resolvePort_), error);
on_resolve(error, iter);
}
void EagerConnection::on_resolve(boost::system::error_code const &err, tcp::resolver::iterator endpoint)
{
LogSpam << "EagerConnection::on_resolve()";
if(!err)
{
tryingLater_ = false;
next:
endpoint_ = *endpoint;
std::stringstream ss;
ss << endpoint_;
endpointName_ = ss.str();
// prefer ipv4, because that's what we bind
if (endpoint_.address().is_v6())
{
++endpoint;
if (endpoint != tcp::resolver::iterator())
{
// the good kind of goto
goto next;
}
}
startConnect(endpoint_);
}
else
{
LogError << "Could not resolve " << resolveHost_ << ":" << resolvePort_;
grab aholdof(mutex_);
tryingLater_ = false;
tryLater();
}
}
void EagerConnection::tryLater()
{
LogSpam << "EagerConnection::tryLater()";
successfulWritesDuringBackoff_ = 1;
if (resolveHost_.size() && resolvePort_.size())
{
if (tryingLater_)
{
LogDebug << "already trying later (backoff is " << backoff_ << " seconds)";
}
else
{
istat::istattime(&tryLaterTime_);
tryingLater_ = true;
backoff_ = (int)((backoff_ + 1) * 1.5);
if (backoff_ > 180)
{
// wait at most 3 minutes, even when backing off
backoff_ = 180;
}
// randomize the backoff
if (backoff_ < 30)
{
backoff_ = backoff_ + (rand() & 3);
}
else
{
backoff_ = backoff_ + (rand() & 15);
}
LogWarning << "Trying again in " << backoff_ << " seconds.";
timer_.expires_from_now(boost::posix_time::seconds(backoff_));
#if BOOST_VERSION >= 106700
timer_.async_wait(boost::asio::bind_executor(strand_, boost::bind(&EagerConnection::startResolve,
#else
timer_.async_wait(strand_.wrap(boost::bind(&EagerConnection::startResolve,
#endif
Tramp(shared_from_this()))));
}
}
}
void EagerConnection::startConnect(tcp::endpoint endpoint)
{
LogNotice << "Connecting to " << endpoint;
socket_.async_connect(endpoint,
#if BOOST_VERSION >= 106700
boost::asio::bind_executor(strand_, boost::bind(&EagerConnection::on_connect, Tramp(shared_from_this()),
#else
strand_.wrap(boost::bind(&EagerConnection::on_connect, Tramp(shared_from_this()),
#endif
placeholders::error, endpoint)));
}
void EagerConnection::on_connect(boost::system::error_code const &err, tcp::endpoint endpoint)
{
if (!err)
{
LogWarning << "Connected to " << endpoint;
if (initialData_.size())
{
outgoing_.insert(outgoing_.begin(), initialData_.begin(), initialData_.end());
}
onConnect_();
startWrite();
startRead();
}
else
{
LogError << "Error connecting to " << endpoint;
grab aholdof(mutex_);
tryLater();
}
}
void EagerConnection::startWrite()
{
LogSpam << "EagerConnection::startWrite()";
if (socket_.is_open())
{
grab aholdof(mutex_);
if (outgoing_.size() && !writePending_ && !tryingLater_)
{
writeBuf_.swap(outgoing_);
outgoing_.clear();
writePending_ = true;
char const *ptr = &writeBuf_[0];
boost::asio::async_write(socket_, boost::asio::buffer(ptr, writeBuf_.size()),
#if BOOST_VERSION >= 106700
boost::asio::bind_executor(strand_, boost::bind(&EagerConnection::on_write,
#else
strand_.wrap(boost::bind(&EagerConnection::on_write,
#endif
Tramp(shared_from_this()), placeholders::error, placeholders::bytes_transferred)));
}
}
}
void EagerConnection::resetBackoffOnSuccessfulWrites()
{
if (backoff_ != 1)
{
++successfulWritesDuringBackoff_;
if (successfulWritesDuringBackoff_ > 3)
{
backoff_ = 1;
}
}
}
void EagerConnection::on_write(boost::system::error_code const &err, size_t xfer)
{
LogSpam << "EagerConnection::on_write(" << xfer << ")";
grab aholdof(mutex_);
writePending_ = false;
if (!!err || xfer < writeBuf_.size())
{
LogWarning << "Short write on socket to " << resolveHost_ << ":" << resolvePort_ << ": " << err;
socket_.close();
onDisconnect_();
tryLater();
return;
}
resetBackoffOnSuccessfulWrites();
onWrite_(xfer);
startWrite();
}
// There is a trade-off between throughput and ability to have many connections open.
// I may want to have 10,000 connections open (monitoring a large cluster of machines, say)
// and I don't want to waste more than 160 MB on such a set-up: 10k * 16k buffers == 160M
void EagerConnection::startRead()
{
LogSpam << "EagerConnect::startRead()";
grab aholdof(mutex_);
if (!readPending_)
{
readPending_ = true;
inBuf_.resize(16384);
char *ptr = &inBuf_[0];
boost::asio::async_read(socket_, boost::asio::buffer(ptr, 16384), boost::asio::transfer_at_least(1),
#if BOOST_VERSION >= 106700
boost::asio::bind_executor(strand_, boost::bind(&EagerConnection::on_read, Tramp(shared_from_this()),
#else
strand_.wrap(boost::bind(&EagerConnection::on_read, Tramp(shared_from_this()),
#endif
placeholders::error, placeholders::bytes_transferred)));
}
}
void EagerConnection::on_read(boost::system::error_code const &err, size_t xfer)
{
LogSpam << "EagerConnection::on_read(" << xfer << ")";
if (!err)
{
if (xfer > 0)
{
grab aholdof(mutex_);
incoming_.insert(incoming_.end(), inBuf_.begin(), inBuf_.begin() + xfer);
}
readPending_ = false;
assert(1 == ++interlock_);
onData_();
assert(0 == --interlock_);
startRead();
}
else
{
if (resolveHost_ != "")
{
LogError << "Socket error for host" << resolveHost_ << "; port" << resolvePort_ << ";" << err;
}
else
{
LogError << "Socket error for endpoint" << endpoint_ << ";" << err;
}
socket_.close();
onDisconnect_();
readPending_ = false;
if (opened_)
{
grab aholdof(mutex_);
tryLater();
}
}
}
std::string const &EagerConnection::endpointName()
{
return endpointName_;
}
EagerConnection *EagerConnection::asEagerConnection()
{
return this;
}
UdpConnectionInfo *EagerConnection::asUdpConnection()
{
return 0;
}