module Redwood
-class SourceError < StandardError; end
+class SourceError < StandardError
+ def initialize *a
+ raise "don't instantiate me!" if SourceError.is_a?(self.class)
+ super
+ end
+end
+class OutOfSyncSourceError < SourceError; end
+class FatalSourceError < SourceError; end
class Source
- ## Implementing a new source is typically quite easy, because Sup
- ## only needs to be able to:
+ ## Implementing a new source should be easy, because Sup only needs
+ ## to be able to:
## 1. See how many messages it contains
- ## 2. Get an arbirtrary message
+ ## 2. Get an arbitrary message
## 3. (optional) see whether the source has marked it read or not
##
## In particular, Sup doesn't need to move messages, mark them as
- ## read, delete them, or anything else. (Well, at some point it will
- ## need to delete them, but that will be an optional capability.)
+ ## read, delete them, or anything else. (Well, it's nice to be able
+ ## to delete them, but that is optional.)
##
## On the other hand, Sup assumes that you can assign each message a
## unique integer id, such that newer messages have higher ids than
## - load_header offset
## - load_message offset
## - raw_header offset
- ## - raw_full_message offset
- ## - next (or each, if you prefer)
+ ## - raw_message offset
+ ## - check
+ ## - next (or each, if you prefer): should return a message and an
+ ## array of labels.
##
## ... where "offset" really means unique id. (You can tell I
## started with mbox.)
##
- ## You can throw SourceErrors from any of those, but we don't catch
- ## anything else, so make sure you catch *all* errors and reraise
- ## them as SourceErrors, and set broken_msg to something if the
- ## source needs to be rescanned.
+ ## All exceptions relating to accessing the source must be caught
+ ## and rethrown as FatalSourceErrors or OutOfSyncSourceErrors.
+ ## OutOfSyncSourceErrors should be used for problems that a call to
+ ## sup-sync will fix (namely someone's been playing with the source
+ ## from another client); FatalSourceErrors can be used for anything
+ ## else (e.g. the imap server is down or the maildir is missing.)
##
- ## Also, be sure to make the source thread-safe, since it WILL be
- ## pummeled from multiple threads at once.
+ ## Finally, be sure the source is thread-safe, since it WILL be
+ ## pummelled from multiple threads at once.
##
- ## Two examples for you to look at, though sadly neither of them is
- ## as simple as I'd like: mbox/loader.rb and imap.rb
-
-
+ ## Examples for you to look at: mbox/loader.rb, imap.rb, and
+ ## maildir.rb.
- ## dirty? described whether cur_offset has changed, which means the
- ## source info needs to be re-saved to sources.yaml.
+ ## let's begin!
##
- ## broken? means no message can be loaded, e.g. IMAP server is
- ## down, mbox file is corrupt and needs to be rescanned, etc.
+ ## dirty? means cur_offset has changed, so the source info needs to
+ ## be re-saved to sources.yaml.
bool_reader :usual, :archived, :dirty
- attr_reader :uri, :cur_offset, :broken_msg
+ attr_reader :uri, :cur_offset
attr_accessor :id
def initialize uri, initial_offset=nil, usual=true, archived=false, id=nil
+ raise ArgumentError, "id must be an integer: #{id.inspect}" unless id.is_a? Fixnum if id
+
@uri = uri
@cur_offset = initial_offset
@usual = usual
@archived = archived
@id = id
@dirty = false
- @broken_msg = nil
end
- def broken?; !@broken_msg.nil?; end
+ def file_path; nil end
+
def to_s; @uri.to_s; end
def seek_to! o; self.cur_offset = o; end
- def reset!
- return if broken?
- begin
- seek_to! start_offset
- rescue SourceError
- end
- end
- def == o; o.to_s == to_s; end
- def done?;
- return true if broken?
- begin
- (self.cur_offset ||= start_offset) >= end_offset
- rescue SourceError => e
- true
- end
- end
- def is_source_for? uri; URI(self.uri) == URI(uri); end
+ def reset!; seek_to! start_offset; end
+ def == o; o.uri == uri; end
+ def done?; start_offset.nil? || (self.cur_offset ||= start_offset) >= end_offset; end
+ def is_source_for? uri; uri == @uri; end
+
+ ## check should throw a FatalSourceError or an OutOfSyncSourcError
+ ## if it can detect a problem. it is called when the sup starts up
+ ## to proactively notify the user of any source problems.
+ def check; end
def each
- return if broken?
- begin
- self.cur_offset ||= start_offset
- until done? || broken? # just like life!
- n, labels = self.next
- raise "no message" unless n
- yield n, labels
- end
- rescue SourceError => e
- self.broken_msg = e.message
+ self.cur_offset ||= start_offset
+ until done?
+ n, labels = self.next
+ raise "no message" unless n
+ yield n, labels
end
end
protected
+ def Source.expand_filesystem_uri uri
+ uri.gsub "~", File.expand_path("~")
+ end
+
def cur_offset= o
@cur_offset = o
@dirty = true
end
-
- def broken_msg= m
- @broken_msg = m
-# Redwood::log "#{to_s}: #{m}"
- end
end
-Redwood::register_yaml(Source, %w(uri cur_offset usual archived id))
-
end