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Retry poll calls on EINTR (#3858)

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When signals are delievered to the process, calls here to poll may be
interrupted and return with a spurious failure.  The call instead should be
restarted.
This commit is contained in:
John Heffner 2022-08-01 12:11:43 -04:00 committed by GitHub
parent 9eae0dff88
commit 86b3305b09
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1 changed files with 33 additions and 18 deletions
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51
sdk/core/azure-core/src/http/curl/curl.cpp
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@ -1,12 +1,22 @@
// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT
#include "azure/core/platform.hpp"
#if defined(AZ_PLATFORM_WINDOWS)
#if !defined(WIN32_LEAN_AND_MEAN)
#define WIN32_LEAN_AND_MEAN
#endif
#if !defined(NOMINMAX)
#define NOMINMAX
#endif
#endif
#include "azure/core/http/curl_transport.hpp"
#include "azure/core/http/http.hpp"
#include "azure/core/http/policies/policy.hpp"
#include "azure/core/http/transport.hpp"
#include "azure/core/internal/diagnostics/log.hpp"
#include "azure/core/platform.hpp"
// Private include
#include "curl_connection_pool_private.hpp"
@ -17,16 +27,11 @@
#include <poll.h> // for poll()
#include <sys/socket.h> // for socket shutdown
#elif defined(AZ_PLATFORM_WINDOWS)
#if !defined(WIN32_LEAN_AND_MEAN)
#define WIN32_LEAN_AND_MEAN
#endif
#if !defined(NOMINMAX)
#define NOMINMAX
#endif
#include <winsock2.h> // for WSAPoll();
#endif
#include <algorithm>
#include <chrono>
#include <string>
#include <thread>
@ -94,25 +99,35 @@ int pollSocketUntilEventOrTimeout(
// we use 1 as arg.
// Cancelation is possible by calling poll() with small time intervals instead of using the
// requested timeout. Default interval for calling poll() is 1 sec whenever arg timeout is
// greater than 1 sec. Otherwise the interval is set to timeout
long interval = 1000; // 1 second
if (timeout < interval)
{
interval = timeout;
}
// requested timeout. The polling interval is 1 second.
static constexpr std::chrono::milliseconds pollInterval(1000); // 1 second
int result = 0;
for (long counter = 0; counter < timeout && result == 0; counter = counter + interval)
auto now = std::chrono::steady_clock::now();
auto deadline = now + std::chrono::milliseconds(timeout);
while (now < deadline)
{
// check cancelation
context.ThrowIfCancelled();
int pollTimeoutMs = static_cast<int>(
std::min(
pollInterval, std::chrono::duration_cast<std::chrono::milliseconds>(deadline - now))
.count());
#if defined(AZ_PLATFORM_POSIX)
result = poll(&poller, 1, interval);
result = poll(&poller, 1, pollTimeoutMs);
if (result < 0 && EINTR == errno)
{
continue;
}
#elif defined(AZ_PLATFORM_WINDOWS)
result = WSAPoll(&poller, 1, interval);
result = WSAPoll(&poller, 1, pollTimeoutMs);
#endif
if (result != 0)
{
return result;
}
now = std::chrono::steady_clock::now();
}
// result can be either 0 (timeout) or > 1 (socket ready)
// result can be 0 (timeout), > 0 (socket ready), or < 0 (error)
return result;
}