1 files changed, 108 insertions, 0 deletions
diff --git a/lib/bundler/compact_index_client.rb b/lib/bundler/compact_index_client.rb
new file mode 100644
index 0000000000..3ed05ca484
--- /dev/null
+++ b/lib/bundler/compact_index_client.rb
@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+require "pathname"
+require "set"
+
+module Bundler
+  class CompactIndexClient
+    DEBUG_MUTEX = Mutex.new
+    def self.debug
+      return unless ENV["DEBUG_COMPACT_INDEX"]
+      DEBUG_MUTEX.synchronize { warn("[#{self}] #{yield}") }
+    end
+
+    class Error < StandardError; end
+
+    require "bundler/compact_index_client/cache"
+    require "bundler/compact_index_client/updater"
+
+    attr_reader :directory
+
+    # @return [Lambda] A lambda that takes an array of inputs and a block, and
+    #         maps the inputs with the block in parallel.
+    #
+    attr_accessor :in_parallel
+
+    def initialize(directory, fetcher)
+      @directory = Pathname.new(directory)
+      @updater = Updater.new(fetcher)
+      @cache = Cache.new(@directory)
+      @endpoints = Set.new
+      @info_checksums_by_name = {}
+      @parsed_checksums = false
+      @mutex = Mutex.new
+      @in_parallel = lambda do |inputs, &blk|
+        inputs.map(&blk)
+      end
+    end
+
+    def names
+      Bundler::CompactIndexClient.debug { "/names" }
+      update(@cache.names_path, "names")
+      @cache.names
+    end
+
+    def versions
+      Bundler::CompactIndexClient.debug { "/versions" }
+      update(@cache.versions_path, "versions")
+      versions, @info_checksums_by_name = @cache.versions
+      versions
+    end
+
+    def dependencies(names)
+      Bundler::CompactIndexClient.debug { "dependencies(#{names})" }
+      in_parallel.call(names) do |name|
+        update_info(name)
+        @cache.dependencies(name).map {|d| d.unshift(name) }
+      end.flatten(1)
+    end
+
+    def spec(name, version, platform = nil)
+      Bundler::CompactIndexClient.debug { "spec(name = #{name}, version = #{version}, platform = #{platform})" }
+      update_info(name)
+      @cache.specific_dependency(name, version, platform)
+    end
+
+    def update_and_parse_checksums!
+      Bundler::CompactIndexClient.debug { "update_and_parse_checksums!" }
+      return @info_checksums_by_name if @parsed_checksums
+      update(@cache.versions_path, "versions")
+      @info_checksums_by_name = @cache.checksums
+      @parsed_checksums = true
+    end
+
+  private
+
+    def update(local_path, remote_path)
+      Bundler::CompactIndexClient.debug { "update(#{local_path}, #{remote_path})" }
+      unless synchronize { @endpoints.add?(remote_path) }
+        Bundler::CompactIndexClient.debug { "already fetched #{remote_path}" }
+        return
+      end
+      @updater.update(local_path, url(remote_path))
+    end
+
+    def update_info(name)
+      Bundler::CompactIndexClient.debug { "update_info(#{name})" }
+      path = @cache.info_path(name)
+      checksum = @updater.checksum_for_file(path)
+      unless existing = @info_checksums_by_name[name]
+        Bundler::CompactIndexClient.debug { "skipping updating info for #{name} since it is missing from versions" }
+        return
+      end
+      if checksum == existing
+        Bundler::CompactIndexClient.debug { "skipping updating info for #{name} since the versions checksum matches the local checksum" }
+        return
+      end
+      Bundler::CompactIndexClient.debug { "updating info for #{name} since the versions checksum #{existing} != the local checksum #{checksum}" }
+      update(path, "info/#{name}")
+    end
+
+    def url(path)
+      path
+    end
+
+    def synchronize
+      @mutex.synchronize { yield }
+    end
+  end
+end