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https://github.com/ClickHouse/ClickHouse.git
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86 lines
1.6 KiB
C++
86 lines
1.6 KiB
C++
#include "AsynchronousBlockInputStream.h"
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#include <Common/setThreadName.h>
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#include <Common/CurrentThread.h>
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namespace DB
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{
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Block AsynchronousBlockInputStream::readImpl()
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{
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/// If there were no calculations yet, calculate the first block synchronously
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if (!started)
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{
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calculate();
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started = true;
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}
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else /// If the calculations are already in progress - wait for the result
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pool.wait();
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if (exception)
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std::rethrow_exception(exception);
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Block res = block;
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if (!res)
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return res;
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/// Start the next block calculation
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block.clear();
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next();
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return res;
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}
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void AsynchronousBlockInputStream::next()
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{
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ready.reset();
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pool.scheduleOrThrowOnError([this, thread_group = CurrentThread::getGroup()]()
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{
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CurrentMetrics::Increment metric_increment{CurrentMetrics::QueryThread};
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try
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{
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if (first)
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setThreadName("AsyncBlockInput");
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/// AsynchronousBlockInputStream is used in Client which does not create queries and thread groups
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if (thread_group)
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CurrentThread::attachToIfDetached(thread_group);
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}
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catch (...)
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{
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exception = std::current_exception();
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ready.set();
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return;
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}
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calculate();
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});
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}
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void AsynchronousBlockInputStream::calculate()
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{
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try
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{
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if (first)
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{
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first = false;
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children.back()->readPrefix();
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}
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block = children.back()->read();
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}
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catch (...)
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{
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exception = std::current_exception();
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}
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ready.set();
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}
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}
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