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 : 1.300.2025 ################################################################################ Copyright (c) René Vaessen / GenXdev Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ################################################################################> 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: $_" } } } } |