Functions/GenXdev.FileSystem/WriteJsonAtomic.ps1
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Part of PowerShell module : GenXdev.FileSystem Original cmdlet filename : WriteJsonAtomic.ps1 Original author : René Vaessen / GenXdev Version : 1.298.2025 ################################################################################ MIT License Copyright 2021-2025 GenXdev Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ################################################################################> function WriteJsonAtomic { [CmdletBinding()] param( [Parameter(Mandatory = $true)] [string]$FilePath, [Parameter(Mandatory = $true)] [hashtable]$Data, [Parameter(Mandatory = $false)] [int]$MaxRetries = 10, [Parameter(Mandatory = $false)] [int]$RetryDelayMs = 200 ) # ensure directory exists $directory = [System.IO.Path]::GetDirectoryName($FilePath) if (-not (Microsoft.PowerShell.Management\Test-Path -LiteralPath $directory)) { $null = GenXdev.FileSystem\Expand-Path $directory -CreateDirectory } # construct file paths for atomic operation $lockFile = "${FilePath}.lock" $tmpFile = "${FilePath}.tmp" $tmp2File = "${FilePath}.tmp2" # attempt atomic write with retries for ($attempt = 0; $attempt -lt $MaxRetries; $attempt++) { try { # clean up stale lock files older than 30 seconds if (Microsoft.PowerShell.Management\Test-Path -LiteralPath $lockFile) { $lockInfo = [System.IO.FileInfo]::new($lockFile) $ageMilliSeconds = ([DateTime]::Now - $lockInfo.LastWriteTime).TotalMilliseconds if ($ageMilliSeconds -gt ($MaxRetries * 10)) { Microsoft.PowerShell.Utility\Write-Verbose ` "Removing stale lock file: $lockFile (age: ${ageMilliSeconds}ms)" Microsoft.PowerShell.Management\Remove-Item ` -LiteralPath $lockFile ` -Force ` -ErrorAction SilentlyContinue } else { # lock is recent, wait and retry throw "File is locked by another process" } } # create lock file $null = Microsoft.PowerShell.Management\New-Item ` -Path $lockFile ` -ItemType File ` -Force ` -ErrorAction Stop try { # write json content to temporary file $jsonContent = $Data | Microsoft.PowerShell.Utility\ConvertTo-Json ` -Depth 10 ` -Compress:$false [System.IO.File]::WriteAllText($tmpFile, $jsonContent, ` [System.Text.Encoding]::UTF8) # perform atomic rename operation if (Microsoft.PowerShell.Management\Test-Path ` -LiteralPath $FilePath) { # rename existing file to .tmp2 Microsoft.PowerShell.Management\Move-Item ` -LiteralPath $FilePath ` -Destination $tmp2File ` -Force ` -ErrorAction Stop } # rename .tmp to actual filename Microsoft.PowerShell.Management\Move-Item ` -LiteralPath $tmpFile ` -Destination $FilePath ` -Force ` -ErrorAction Stop # delete backup file if it exists if (Microsoft.PowerShell.Management\Test-Path ` -LiteralPath $tmp2File) { Microsoft.PowerShell.Management\Remove-Item ` -LiteralPath $tmp2File ` -Force ` -ErrorAction SilentlyContinue } # operation successful, break retry loop break } finally { # always remove lock file if (Microsoft.PowerShell.Management\Test-Path ` -LiteralPath $lockFile) { Microsoft.PowerShell.Management\Remove-Item ` -LiteralPath $lockFile ` -Force ` -ErrorAction SilentlyContinue } } } catch { # log retry attempt Microsoft.PowerShell.Utility\Write-Verbose ` "Write attempt $($attempt + 1) failed: $($_.Exception.Message)" # clean up temporary files on error foreach ($tempFile in @($tmpFile, $tmp2File, $lockFile)) { if (Microsoft.PowerShell.Management\Test-Path ` -LiteralPath $tempFile) { Microsoft.PowerShell.Management\Remove-Item ` -LiteralPath $tempFile ` -Force ` -ErrorAction SilentlyContinue } } # wait before retry unless this is the last attempt if ($attempt -lt ($MaxRetries - 1)) { Microsoft.PowerShell.Utility\Start-Sleep ` -Milliseconds $RetryDelayMs } else { # final attempt failed, throw error throw "Failed to write JSON file after ${MaxRetries} attempts: $_" } } } } |