Selective conversion via timestamps, -f option (fix #2)

README.md

@@ -28,14 +28,23 @@ svgink --pdf -o pdf filename1.svg filename2.svg
 
 A major advantage of `svgink` is that it quickly converts many SVG files.
 
-First, `svgink` uses Inkscape's
+First, `svgink` skips converting SVG files that are older than the
+corresponding PDF/PNG file (similar to `make`).
+You can override this behavior via the `--force` command-line option,
+which forces all conversions to be done.
+This is useful if you update Inkscape, update `svgink`, or
+a conversion failed and somehow generated a bad file.
+(Alternatively, you can `touch` the relevant SVG files
+or `rm` the relevant PDF/PNG files.)
+
+Second, `svgink` uses Inkscape's
 [shell protocol](https://wiki.inkscape.org/wiki/Using_the_Command_Line#Shell_mode)
 to run a sequence of conversions with a single Inkscape process.
 This is much faster than running Inkscape individually on each SVG file
 (especially on Windows, where spawning a process takes seconds),
-which is what might happen most naturally with a Makefile.
+which is what might happen most naturally with conversions driven by `make`.
 
-Second, `svgink` runs multiple Inkscape processes to exploit multicore CPUs.
+Third, `svgink` runs multiple Inkscape processes to exploit multicore CPUs.
 By default, it runs half as many Inkscape processes as there are logical cores
 on your machine (to account for typical hyperthreading which presents *n*
 physical cores as 2 *n* logical cores).
@@ -78,6 +87,7 @@ Usage: svgink (...options and filenames...)
 Filenames should specify SVG files.
 Optional arguments:
   -h / --help           Show this help message and exit.
+  -f / --force          Force conversion even if output newer than SVG input
   -o DIR / --output DIR Write all output files to directory DIR
   --op DIR / --output-pdf DIR   Write all .pdf files to directory DIR
   --oP DIR / --output-png DIR   Write all .png files to directory DIR
@@ -172,6 +182,7 @@ The API provides two classes:
 The constructors for `SVGProcessor` and `Inkscape` take a single optional
 argument, which is a settings object.  It can have the following properties:
 
+* `force`: Whether to force conversion, even if SVG file is older than target.
 * `inkscape`: Path to inkscape.  Default searches PATH for `inkscape`.
 * `jobs`: Maximum number of Inkscapes to run in parallel.
   Default = half the number of logical CPUs

svgink.coffee

@@ -6,6 +6,8 @@ child_process = require 'child_process'
 fs = require 'fs/promises'
 
 defaultSettings =
+  ## Whether to force conversion, even if SVG file is older than target.
+  force: false
   ## Path to inkscape.  Default searches PATH.
   inkscape: 'inkscape'
   ## Maximum number of Inkscapes to run in parallel.
@@ -161,19 +163,34 @@ class SVGProcessor
     @inkscapes = []
     @queue = []
     @spawning = false
+    @jobs = 0
   convert: (input, output) ->
-    ## Convert input filename to output filename, and then sanitize.
-    ## Returns a Promise.
+    ## Convert input filename to output filename, and then sanitize,
+    ## unless output is newer than input or forced.  Returns a Promise.
+    @jobs++
     new Promise (resolve, reject) =>
       for filename in [input, output]
         if invalidFilename filename
+          jobs--
           return reject new InkscapeError "Inkscape shell does not support filenames with semicolons or leading/trailing spaces: #{filename}"
-      @queue.push {input, output, resolve, reject}
-      @update()
+      ## Compare input and output modification times, unless forced.
+      unless @settings.force
+        try
+          outputStat = await fs.stat output
+          inputStat = await fs.stat input
+      unless inputStat? and outputStat? and inputStat.mtime < outputStat.mtime
+        @queue.push {input, output, resolve, reject}
+        @update()
+      else
+        @jobs--
+        resolve {skip: true}
+        @update() if @closing  # resolve close() in case last job is skipped
+      undefined
   run: (job) ->
     ## Queue job for Inkscape to run.  Returns a Promise.
     ## Job can be a string to send to the shell, or an object with
     ## `input` and `output` properties, for conversion (without sanitization).
+    @jobs++
     job = {job} if typeof job == 'string'
     new Promise (resolve, reject) =>
       @queue.push {...job, resolve, reject}
@@ -188,8 +205,9 @@ class SVGProcessor
     ## Filter out any Inkscape processes that died, e.g. from idle timeout.
     @inkscapes = (inkscape for inkscape in @inkscapes when not inkscape.dead)
     ## Check for completed closing.
-    if @closing and not @queue.length and
-       @inkscapes.every (inkscape) -> not inkscape.job?
+    if @closing and @jobs <= 0
+      #and not @queue.length and
+      #@inkscapes.every (inkscape) -> not inkscape.job?
       ## Schedule close() promise to resolve after job promise resolves.
       setTimeout (=> @closing()), 0
       return
@@ -228,6 +246,8 @@ class SVGProcessor
       data
     .then (data) =>
       job.resolve data
+      @jobs--
+      @update()
     .catch (error) =>
       job.reject error
   sanitize: (output) ->
@@ -257,6 +277,7 @@ Documentation: https://github.com/edemaine/svgink
 Filenames should specify SVG files.
 Optional arguments:
   -h / --help           Show this help message and exit.
+  -f / --force          Force conversion even if output newer than SVG input
   -o DIR / --output DIR Write all output files to directory DIR
   --op DIR / --output-pdf DIR   Write all .pdf files to directory DIR
   --oP DIR / --output-png DIR   Write all .png files to directory DIR
@@ -274,14 +295,20 @@ main = (args = process.argv[2..]) ->
   formats = []
   outputDir = null
   outputDirExt = {}
-  files = skip = 0
+  files =
+    input: 0
+    output: 0
+    skip: 0
+  skip = 0
   for arg, i in args
     if skip
       skip--
       continue
     switch arg
       when '-h', '--help'
         help()
+      when '-f', '--force'
+        settings.force = true
       when '-i', '--inkscape'
         skip = 1
         settings.inkscape = args[i+1]
@@ -308,9 +335,10 @@ main = (args = process.argv[2..]) ->
         else
           console.warn "Invalid argument to --jobs: #{args[i+1]}"
       else
-        files++
+        files.input++
         input = arg
         for format in formats
+          files.output++
           output = path.parse input
           delete output.base
           if output.ext != ".#{format}"
@@ -325,9 +353,13 @@ main = (args = process.argv[2..]) ->
           do (input, output) ->
             processor.convert input, output
             .then (data) ->
-              console.log "* #{input} -> #{output}"
-              console.log data.stdout if data.stdout
-              console.log data.stderr if data.stderr
+              if data.skip
+                files.skip++
+                console.log "- #{input} -> #{output} (skipped)"
+              else
+                console.log "* #{input} -> #{output}"
+                console.log data.stdout if data.stdout
+                console.log data.stderr if data.stderr
             .catch (error) ->
               console.log "! #{input} -> #{output} FAILED"
               console.log error
@@ -339,7 +371,8 @@ main = (args = process.argv[2..]) ->
     console.log '! Not enough filename arguments'
     help()
   else
-    console.log "> Converted #{files} SVG files into #{files * formats.length} files in #{Math.round((new Date) - start) / 1000} seconds"
+    console.log "> Converted #{files.input} SVG files into #{files.output} files (#{files.output - files.skip} updated) in #{Math.round((new Date) - start) / 1000} seconds"
+    console.log "> Skipped #{files.skip} conversions.  To force conversion, use --force" if files.skip
 
 module.exports = {
   defaultSettings