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125 lines
4.1 KiB
C++
125 lines
4.1 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of rippled: https://github.com/ripple/rippled
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Copyright (c) 2012, 2013 Ripple Labs Inc.
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#ifndef RIPPLE_RPC_YIELD_H_INCLUDED
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#define RIPPLE_RPC_YIELD_H_INCLUDED
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#include <ripple/core/JobQueue.h>
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#include <ripple/json/Output.h>
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#include <beast/win32_workaround.h>
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#include <boost/coroutine/all.hpp>
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#include <functional>
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namespace ripple {
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class JobQueue;
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class Section;
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namespace RPC {
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/** See the README.md in this directory for more information about how
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the RPC yield mechanism works.
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*/
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/** Callback: do something and eventually return. */
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using Callback = std::function <void ()>;
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static
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Callback const emptyCallback ([] () {});
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/** Continuation: do something, guarantee to eventually call Callback. */
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using Continuation = std::function <void (Callback const&)>;
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/** Suspend: suspend execution, pending completion of a Continuation. */
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using Suspend = std::function <void (Continuation const&)>;
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/** Wrap an Output so it yields after approximately `chunkSize` bytes.
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chunkedYieldingOutput() only yields after a call to output(), so there might
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more than chunkSize bytes sent between calls to yield().
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chunkedYieldingOutput() also only yields before it's about to output more
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data. This is to avoid the case where you yield after outputting data, but
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then never send more data.
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*/
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Json::Output chunkedYieldingOutput (
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Json::Output const&, Callback const&, std::size_t chunkSize);
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/** Yield every yieldCount calls. If yieldCount is 0, never yield. */
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class CountedYield
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{
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public:
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CountedYield (std::size_t yieldCount, Callback const& yield);
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void yield();
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private:
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std::size_t count_ = 0;
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std::size_t const yieldCount_;
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Callback const yield_;
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};
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/** When do we yield when performing a ledger computation? */
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struct YieldStrategy
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{
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enum class Streaming {no, yes};
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enum class UseCoroutines {no, yes};
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/** Is the data streamed, or generated monolithically? */
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Streaming streaming = Streaming::no;
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/** Are results generated in a coroutine? If this is no, then the code can
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never yield. */
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UseCoroutines useCoroutines = UseCoroutines::no;
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/** How many bytes do we emit before yielding? 0 means "never yield due to
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number of bytes sent". */
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std::size_t byteYieldCount = 0;
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/** How many accounts do we process before yielding? 0 means "never yield
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due to number of accounts processed." */
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std::size_t accountYieldCount = 0;
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/** How many transactions do we process before yielding? 0 means "never
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yield due to number of transactions processed." */
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std::size_t transactionYieldCount = 0;
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};
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/** Create a yield strategy from a configuration Section. */
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YieldStrategy makeYieldStrategy (Section const&);
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/** Return a continuation that runs a Callback on a Job Queue with a given
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name and JobType. */
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Continuation callbackOnJobQueue (
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JobQueue&, std::string const& jobName, JobType);
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/** Return a Callback that will suspend and then run a continuation. */
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inline
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Callback suspendForContinuation (
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Suspend const& suspend, Continuation const& continuation)
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{
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return suspend
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? Callback ([=] () { suspend (continuation); })
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: emptyCallback;
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}
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} // RPC
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} // ripple
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#endif
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