如何解决如何在PHP中排队请求？
我尝试使用下面的代码对请求进行排队，但无法正常工作！
<?php
$Sleep_Time = "10";
if (isset($_POST["String"])){
$File = "Edit_File_Content.txt";
while(file_exists($File . "_Locked")) {
//wait,do nothing until "Edit_File_Content.txt_Locked" file is deleted
}
file_put_contents($File . "_Locked",""); //create new file with same name with "_Locked" in the end (second parameter must be specified)
$File_Content = file_get_contents($File);
$File_Content .= $_POST["String"];
sleep($Sleep_Time); //sleep for x seconds
file_put_contents($File,$File_Content);
unlink($File . "_Locked"); //delete the above "_Locked" file
echo "String Added";
return;
}
?>
Each request takes <?php echo $Sleep_Time ?> seconds to finish!
<br><br>
<input type="button" value="Add A" onclick='Add_String("A")'>
<input type="button" value="Add B" onclick='Add_String("B")'>
<br><br>
<div id="Ajax_Response">Ajax Response:<br><br></div>
<script>
function Add_String(Option){ //____________________________
var http = new XMLHttpRequest();
http.open('POST',""); //blank url (send to same page)
http.setRequestHeader('Content-type','application/x-www-form-urlencoded'); //necessary to send "String" POST key below to php
http.onreadystatechange = function(){
if (this.readyState === 4) { //"4",request finished and response is ready!
document.getElementById("Ajax_Response").innerHTML += this.responseText + "<br>";
}
};
http.send('String=' + Option);
}
</script>
下图显示了同时单击5次“添加A”和“添加B”时的“ Ajax响应”：
所有请求完成后，“ Edit_File_Content.txt”文件将仅包含“ AA”，而不是“ AAAAABBBBB”字符串！
关于如何在php中有效地将请求排队的任何建议？
解决方法
我写了下面的“ Check_File_Write_Queue（）”函数，到目前为止，看来还可以！
同时单击5次“添加A”和“添加B”时，所有请求完成后，“ Edit_File_Content.txt”文件将按预期包含“ AAAAABBBBB”字符串！
无论如何，始终欢迎更好的解决方案！
<?php
$Sleep_Time = "3";
if (isset($_POST["String"])){
$File = "Edit_File_Content.txt";
$File_Write_Request = Check_File_Write_Queue($File); //add a new write request to a file and wait here until older requests are finhished
$File_Content = file_get_contents($File);
$File_Content .= $_POST["String"];
sleep($Sleep_Time); //sleep for x seconds
file_put_contents($File,$File_Content);
Check_File_Write_Queue($File_Write_Request,"Delete");
//if the above line is not used,the "register_shutdown_function()" used in the function will ensure that the "$File_Write_Request" will be removed when script exits!
echo "String Added";
return;
}
function Check_File_Write_Queue($File,$Option = "") { //____________________________
$Files_Write_Queue = realpath("Edit_File_Content_Check_File_Write_Queue_List.txt");
if ($Option == "Delete" || $Option == "delete"){
$File_Content = file_get_contents($Files_Write_Queue);
$File_Content = str_replace($File,"",$File_Content);
file_put_contents($Files_Write_Queue,$File_Content);
return;
}
$File = realpath($File);
$Request_Id = microtime() . " " . bin2hex(random_bytes(10));
$Write_Request = $File . "<<<<" . $Request_Id . ">>>>\r\n";
file_put_contents($Files_Write_Queue,$Write_Request,FILE_APPEND);
//to prevent errors\issues,"realpath()" should be used in "register_shutdown_function()"
register_shutdown_function(function() use ($Files_Write_Queue,$Write_Request){
$File_Content = file_get_contents($Files_Write_Queue);
$File_Content = str_replace($Write_Request,$File_Content);
});
while(1) { //1=Infinite loop
$File_Content = file_get_contents($Files_Write_Queue);
preg_match('/' . preg_quote($File,'/') . '<<<<(.*?)>>>>/',$File_Content,$match);
if (@$match[1] == $Request_Id){return $Write_Request;}
}
}
?>
Each request takes <?php echo $Sleep_Time ?> seconds to finish!
<br><br>
<input type="button" value="Add A" onclick='Add_String("A")'>
<input type="button" value="Add B" onclick='Add_String("B")'>
<br><br>
<div id="Ajax_Response">Ajax Response:<br><br></div>
<script>
function Add_String(Option){ //____________________________
var http = new XMLHttpRequest();
http.open('POST',""); //blank url (send to same page)
http.setRequestHeader('Content-type','application/x-www-form-urlencoded'); //necessary to send "String" POST key below to php
http.onreadystatechange = function(){
if (this.readyState === 4) { //"4",request finished and response is ready!
document.getElementById("Ajax_Response").innerHTML += this.responseText + "<br>";
}
};
http.send('String=' + Option);
}
</script>
在上一个答案中，我使用了“ Check_File_Write_Queue（）”函数，但有人提醒我可以使用PHP内置函数“ flock（）”来做到这一点，这是正确的，但我注意到一些有趣的事情。 ，“ Check_File_Write_Queue（）”比“ flock（）”更精确，例如，如果一次单击“添加A” 5次，然后一次单击“添加B” 5次，则“ Edit_File_Content.txt”中的输出“ Check_File_Write_Queue（）”中的文件始终为“ AAAAABBBBB”，而“ flock（）”中的文件始终为“ AAABBABBBA”，“ BBAABBAABA”，“ ABABBBAABA”，“ BBBBBAAAAA”，“ AAAAABBBBB”等，这表示“ Check_File_Write_Queue（）”始终以正确的顺序处理请求，而“ flock（）”有时会正确执行，有时则不会！
无论如何，下面的代码是使用PHP内置函数“ flock（）”而不是“ Check_File_Write_Queue（）”函数的另一种解决方案：
<?php
$Sleep_Time = "3";
if (isset($_POST["String"])){
$File = "Edit_File_Content.txt";
$File_Handle = fopen("$File","r");
if(flock($File_Handle,LOCK_EX)){ //on success,this script execution waits here until older scripts in queue unlock the file
$File_Content = file_get_contents($File);
$File_Content .= $_POST["String"];
sleep($Sleep_Time); //sleep for x seconds
file_put_contents($File,$File_Content);
flock($File_Handle,LOCK_UN); //unlock the file so new scripts in queue can continue execution
echo "flock() success [String Added]";
}else{echo "flock() Failed";}
fclose($File_Handle);
return;
}
?>
Each request takes <?php echo $Sleep_Time ?> seconds to finish!
<br><br>
<input type="button" value="Add A" onclick='Add_String("A")'>
<input type="button" value="Add B" onclick='Add_String("B")'>
<br><br>
<div id="Ajax_Response">Ajax Response:<br><br></div>
<script>
function Add_String(Option){ //____________________________
var http = new XMLHttpRequest();
http.open('POST','application/x-www-form-urlencoded'); //necessary to send "String" POST key below to php
http.setRequestHeader('Content-type',request finished and response is ready!
document.getElementById("Ajax_Response").innerHTML += this.responseText + "<br>";
}
};
http.send('String=' + Option);
}
</script>
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