Add basic debug support

NEWS.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Added
+
+* Write debug output to file, if the `THERMITE_DEBUG_FILENAME` environment variable is set
+
 ### Changed
 
 * Relaxed rake version requirement

README.md

@@ -67,6 +67,11 @@ repository contains an example of using Thermite with [ruru](https://github.com/
 to provide a `String.blank?` speedup extension. While the example uses ruru, this gem should be
 usable with any method of integrating Rust and Ruby that you choose.
 
+### Troubleshooting
+
+Debug statements can be written to a file specified by the `THERMITE_DEBUG_FILENAME` environment
+variable.
+
 ## FAQ
 
 ### Why is it named Thermite?

lib/thermite/config.rb

@@ -36,6 +36,13 @@ def initialize(options = {})
       @options = options
     end
 
+    #
+    # Location to emit debug output, if not `nil`. Defaults to `nil`.
+    #
+    def debug_filename
+      @debug_filename ||= ENV['THERMITE_DEBUG_FILENAME']
+    end
+
     #
     # The file extension of the compiled shared Rust library.
     #

lib/thermite/github_release_binary.rb

@@ -58,7 +58,9 @@ def download_binary
     def download_cargo_version_from_github_release
       version = config.toml[:package][:version]
       tag = options.fetch(:git_tag_format, 'v%s') % version
-      if (tgz = download_binary_from_github_release(github_download_uri(tag, version), version))
+      uri = github_download_uri(tag, version)
+      if (tgz = download_binary_from_github_release(uri, version))
+        debug "Unpacking GitHub release from Cargo version: #{File.basename(uri)}"
         unpack_tarball(tgz)
         true
       end
@@ -73,6 +75,7 @@ def download_latest_binary_from_github_release
       each_github_release(github_uri) do |version, download_uri|
         tgz = download_binary_from_github_release(download_uri, version)
         next unless tgz
+        debug "Unpacking GitHub release: #{File.basename(download_uri)}"
         unpack_tarball(tgz)
         installed_binary = true
         break
@@ -123,6 +126,7 @@ def unpack_tarball(tgz)
       tar.each do |entry|
         path = entry.header.name
         next if path.end_with?('/')
+        debug "Unpacking file: #{path}"
         File.open(path, 'wb') do |f|
           f.write(entry.read)
         end

lib/thermite/tasks.rb

@@ -24,6 +24,7 @@
 require 'thermite/config'
 require 'thermite/github_release_binary'
 require 'thermite/package'
+require 'thermite/util'
 
 #
 # Helpers for Rust-based Ruby extensions.
@@ -41,6 +42,7 @@ class Tasks < Rake::TaskLib
     include Thermite::Cargo
     include Thermite::GithubReleaseBinary
     include Thermite::Package
+    include Thermite::Util
 
     #
     # The configuration used for the Rake tasks.

lib/thermite/util.rb

@@ -0,0 +1,34 @@
+# -*- encoding: utf-8 -*-
+# frozen_string_literal: true
+#
+# Copyright (c) 2016 Mark Lee and contributors
+#
+# 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.
+
+module Thermite
+  #
+  # Utility methods
+  #
+  module Util
+    def debug(msg)
+      # Should probably replace with a Logger
+      if config.debug_filename
+        @debug ||= File.open(config.debug_filename, 'w')
+        @debug.write("#{msg}\n")
+      end
+    end
+  end
+end