Пример очереди FIFO

array_shift
array_push
json_encode
json_decode
google.com

 

Никакой фантазии.

PHP:

1. <?php
2. /**
3. * Function for replacing elements in json-file
4. * Writing rows as json strings into file
5. * Watching for overflowing max rows count and popping top elements
6. *
7. * @param $filename string File name, possible absolute path, not tested, possibly works
8. * @param $rows array|string Rows with already json_encode() lines, or one line
9. * @param $rowsMax int Default rows limit for a file
10. * @return void
11. */
12. function AddRowsToJsonFileWithRowsLimitByLine($filename, $rows, $rowsMax = 5){
13.     if(!is_file($filename))
14.         file_put_contents($filename, "[" . PHP_EOL . "]" . PHP_EOL);
15.     // str -> arr
16.     if(!is_array($rows))
17.         $rows = [$rows];
18.  
19.     // in case count of incoming lines higher than our limit push diff from lines
20.     if (($rowsCount = count($rows)) > $rowsMax && $rowsCount = $rowsMax)
21.         $rows = array_slice($rows, -1, $rowsMax);
22.  
23.     // count total lines in parsing file
24.     // wc -l easy hand
25.     // if file not exists, or something, we take our limit as current lines count
26.     $currentRowsCount = (
27.         $currentLinesCount = (explode(" ", `wc -l $filename`)[0] ?? 0)
28.     ) < 2 ?
29.         0 :
30.         $currentLinesCount - 2;
31.  
32.     // calculate shifting
33.     $shiftLinesCount = $rowsCount + $currentRowsCount - $rowsMax;
34.  
35.     // source file
36.     $sourceFile = fopen($filename, "r");
37.     // temp file
38.     $tempFile = fopen($filename . ".tmp", "w+");
39.     // ignoring bracers cause they are not rows, and write them directly
40.     fwrite($tempFile, "[" . PHP_EOL);
41.  
42.     while(!feof($sourceFile)){
43.         $line = trim(fgets($sourceFile));
44.         // skip lines for shifting
45.         if(@$a++ > $shiftLinesCount && !in_array($line, ["[", "]"]) && $line)
46.             fwrite($tempFile, $line . (str_ends_with($line, ",") ? "" : ",") . PHP_EOL);
47.     }
48.  
49.     // write new rows and other
50.     fwrite($tempFile, implode("," . PHP_EOL, $rows) . PHP_EOL . "]" . PHP_EOL);
51.  
52.     fclose($sourceFile);
53.     fclose($tempFile);
54.  
55.     // backup dude, yeah
56.     copy($filename, $filename . ".back");
57.     // moving our temp file as new source
58.     copy($filename . ".tmp", $filename);
59.     // remove temporal
60.     unlink($filename . ".tmp");
61. }
62.  
63. AddRowsToJsonFileWithRowsLimitByLine("file.json", [
64.     json_encode(["first_line_in_add_batch" => date("Y.m.d H:i:s")]),
65.     json_encode(["second_line_in_add_batch" => date("Y.m.d H:i:s")]),
66.     json_encode(["third_line_in_add_batch" => date("Y.m.d H:i:s")]),
67. ]);