DM Lua: move etag cache management to own class.

Also remove downloadCount and failedCount insanity.

threaded-libcurl/DownloadManager.moon

@@ -111,6 +111,55 @@ sanitizeFile = ( filename, acceptDir ) ->
 
  return dir .. file
 
+class ETagCache
+ -- DM class ensure cacheDir is an absolute file path and ends with a /.
+ new: ( cacheDir ) =>
+ @cacheDir = cacheDir
+
+ cachedFile: ( cacheName ) =>
+ return @cacheDir .. cacheName
+
+ cachedFileExists: ( cacheName ) =>
+ if cacheName == nil
+ return false
+
+ file = io.open @cachedFile( cacheName ), 'rb'
+ if file == nil
+ return false
+ file\close!
+ return true
+
+ copyFile = ( source, target ) ->
+ input, msg = io.open source, 'rb'
+ if input == nil
+ return input, msg
+ -- assert input, msg
+ output, msg = io.open target, 'wb'
+ if output == nil
+ input\close!
+ return output, msg
+ -- assert output, msg
+ err, msg = output\write input\read '*a'
+ if err == nil
+ input\close!
+ output\close!
+ return err, msg
+
+ input\close!
+ output\close!
+ return true
+
+ useCache: ( download ) =>
+ err, msg = copyFile @cachedFile( download.etag ), download.outfile
+ if err == nil
+ return err, msg
+ return true
+
+ cache: ( download ) =>
+ err, msg = copyFile download.outfile, @cachedFile download.etag
+ if err == nil
+ return err, msg
+ return true
 
 class DownloadManager
  @version = 0x000400
@@ -141,40 +190,11 @@ class DownloadManager
  new: ( etagCacheDir ) =>
  @manager = ffi.gc DM.newDM!, freeManager
  @downloads = { }
- @downloadCount = 0
  @failedDownloads = { }
- @failedCount = 0
  if etagCacheDir
  result, message = sanitizeFile etagCacheDir\gsub( "[/\\]*$", "/", 1 ), true
  assert message == nil, message
- @cacheDir = result
- getCachedFile = ( etag ) =>
- return @cacheDir .. etag
-
- copyFile = ( source, target ) ->
- -- actually handling errors is for big chumps.
- input, msg = io.open source, 'rb'
- assert input, msg
- output, msg = io.open target, 'wb'
- assert output, msg
- err, msg = output\write input\read '*a'
- assert err, msg
- input\close!
- output\close!
-
- etagCacheCheck = ( manager ) =>
- source = getCachedFile manager, @newEtag
- -- if the newEtag matches the provided etag then nothing was
- -- actually downloaded, so we need to copy the cached file to the
- -- expected output.
- if @newEtag == @etag
- -- should probably check if source exists.
- copyFile source, @outfile
-
- -- otherwise, the file was downloaded and we need to copy it into
- -- our etag cache directory.
- else
- copyFile @outfile, source
+ @cache = ETagCache result
 
  addDownload: ( url, outfile, sha1, etag ) =>
  return nil, msgs.notInitialized unless DM
@@ -193,11 +213,19 @@ class DownloadManager
  else
  sha1 = nil
 
+ if etag and "string" != type etag
+ etag = nil
+ if etag and @cache and not @cache\cachedFileExists etag
+ -- if cached file does not exist, do not pass in an etag.
+ etag = nil
 
- DM.addDownload @manager, url, outfile, sha1, cEtag
- @downloadCount += 1
- @downloads[@downloadCount] = { id: @downloadCount, :url, :outfile, :sha1, :etag, :cEtag }
- return @downloads[@downloadCount]
+ id = DM.addDownload @manager, url, outfile, sha1, etag
+ if id == 0
+ return nil, "Could not add download for some reason."
+
+ download = { :id, :url, :outfile, :sha1, :etag }
+ table.insert @downloads, download
+ return download
 
  progress: =>
  return nil, msgs.notInitialized unless DM
@@ -215,8 +243,6 @@ class DownloadManager
  DM.clear @manager
  @downloads = {}
  @failedDownloads = {}
- @downloadCount = 0
- @failedCount = 0
 
  waitForFinish: ( callback ) =>
  return nil, msgs.notInitialized unless DM
@@ -226,27 +252,30 @@ class DownloadManager
  return
  sleep!
 
- @failedCount = 0
- for i = 1, @downloadCount
- download = @downloads[i]
- if download.cEtag != nil
- if download.cEtag[0] != nil
- download.newEtag = ffi.string download.cEtag[0]
- -- I think this actually leaks the string at cEtag[0].
- download.cEtag = nil
+ pushFailed = ( download, message ) ->
+ download.failed = true
+ download.error = message
+ table.insert @failedDownloads, download
+
+ -- all downloads are finished at this point
+ for download in *@downloads
 
- err = DM.getError @manager, i
+ err = DM.getError @manager, download.id
  if err != nil
- @failedCount += 1
- @failedDownloads[@failedCount] = download
- download.error = ffi.string err
- download.failed = true
-
- if @cacheDir and download.newEtag and not download.failed
- err, msg = pcall etagCacheCheck, download, @
- if not err
- download.error = "Etag cache check failed with message: " .. msg
- download.failed = true
+ pushFailed download, ffi.string err
+
+ if @cache
+ if DM.fileWasCached download.id
+ err, msg = @cache\useCache download
+ if err == nil
+ pushFailed download, "Couldn't use cache. Message: " .. msg
+
+ else
+ newETag = DM.getETag download.id
+ if newETag != nil
+ download.etag = ffi.string newETag
+ -- not technically an error if this fails
+ @cache\cache download
 
  if "function" == type download.callback
  download\callback @