93 lines
3.7 KiB
MQL5
93 lines
3.7 KiB
MQL5
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//+------------------------------------------------------------------+
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//| FileFlush.mq5 |
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//| Copyright 2021, MetaQuotes Ltd. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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#property script_show_inputs
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// NB: PRTF clears up _LastError, so don't use it in code blocks
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// using conditions based on _LastError
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#include "..\..\Include\PRTF.mqh"
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input bool EnableFlashing = false;
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input bool UseCommonFolder = false;
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const string dataport = "MQL5Book/dataport";
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const int flag = UseCommonFolder ? FILE_COMMON : 0;
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//+------------------------------------------------------------------+
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//| Script program start function |
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//+------------------------------------------------------------------+
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void OnStart()
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{
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Print("\n*");
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// make initial setup
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bool modeWriter = true; // by default script starts to write data
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int count = 0; // number of writes/reads
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// create new file for writing or empty existing one for "sender" role
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int handle = PRTF(FileOpen(dataport,
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FILE_BIN | FILE_WRITE | FILE_SHARE_READ | flag));
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// if writing is impossible, another instance of the script is
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// already writing most likely, so try to read the same file
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if(handle == INVALID_HANDLE)
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{
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// check if the file can be read, if so then assuming "receiver" role
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handle = PRTF(FileOpen(dataport,
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FILE_BIN | FILE_READ | FILE_SHARE_WRITE | FILE_SHARE_READ | flag));
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if(handle == INVALID_HANDLE)
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{
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Print("Can't open file"); // this shouldn't be, something is wrong
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return;
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}
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modeWriter = false; // switch the mode
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}
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// run main loop until user cancels it
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while(!IsStopped())
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{
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long temp = 0;
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if(modeWriter)
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{
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temp = TimeLocal(); // get current local datetime
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// append new timestamp every 5 seconds
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FileWriteLong(handle, temp);
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count++;
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if(EnableFlashing)
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{
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FileFlush(handle);
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}
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Print(StringFormat("Written[%d]: %I64d", count, temp));
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}
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else
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{
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ResetLastError();
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// read out all the file contents written by the sender
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// since we have read the file last time (approx. 5 seconds ago)
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// or from very beginning if this is first time we read the file;
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// NB: you may want to implement another logic, e.g.
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// skip pre-existed data and start reading new additions only
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while(true) // read until end of data, then break the loop
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{
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bool reportedEndBeforeRead = FileIsEnding(handle);
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ulong reportedTellBeforeRead = FileTell(handle);
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// metadata about file size remains the same
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// from the moment when the file was open for reading,
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// so do not call FileSeek(handle, 0, SEEK_END)
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// to keep reading past the End Of File (EOF)
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temp = FileReadLong(handle);
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// if there is no more data, we'll get error 5015 (ERR_FILE_READERROR)
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if(_LastError) break;
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// here we got data without error
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count++;
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Print(StringFormat("Read[%d]: %I64d\t"
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"(size=%I64d, before=%I64d(%s), after=%I64d)",
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count, temp,
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FileSize(handle), reportedTellBeforeRead,
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(string)reportedEndBeforeRead, FileTell(handle)));
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}
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}
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Sleep(5000);
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}
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}
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//+------------------------------------------------------------------+
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