Merge remote-tracking branch 'origin/master'

doc/design/assistant/blog/day_61__network_connection_detection.mdwn

@@ -0,0 +1,36 @@
+Today, added a thread that deals with recovering when there's been a loss
+of network connectivity. When the network's down, the normal immediate
+syncing of changes of course doesn't work. So this thread detects when the
+network comes back up, and does a pull+push to network remotes, and
+triggers scanning for file content that needs to be transferred.
+
+I used dbus again, to detect events generated by both network-manager and
+wicd when they've sucessfully brought an interface up. Or, if they're not
+available, it polls every 30 minutes.
+
+When the network comes up, in addition to the git pull+push, it also
+currently does a full scan of the repo to find files whose contents
+need to be transferred to get fully back into sync.
+
+I think it'll be ok for some git pulls and pushes to happen when
+moving to a new network, or resuming a laptop (or every 30 minutes when
+resorting to polling). But the transfer scan is currently really too heavy
+to be appropriate to do every time in those situations. I have an idea for
+avoiding that scan when the remote's git-annex branch has not changed. But
+I need to refine it, to handle cases like this:
+
+1. a new remote is added
+2. file contents start being transferred to (or from it)
+3. the network is taken down
+4. all the queued transfers fail
+5. the network comes back up
+6. the transfer scan needs to know the remote was not all in sync
+   before #3, and so should do a full scan despite the git-annex branch
+   not having changed
+
+---
+
+Doubled the ram in my netbook, which I use for all development. Yesod needs
+rather a lot of ram to compile and link, and this should make me quite a
+lot more productive. I was struggling with OOM killing bits of chromium
+during my last week of development.

doc/design/assistant/blog/day_61__network_connection_detection/comment_1_09b58f41a8d48f218619711ee19511ac._comment

@@ -0,0 +1,8 @@
+[[!comment format=mdwn
+ username="https://www.google.com/accounts/o8/id?id=AItOawmubB1Sj2rwFoVdZYvGV0ACaQUJQyiJXJI"
+ nickname="Paul"
+ subject="Amazon Glacier"
+ date="2012-08-23T06:32:24Z"
+ content="""
+Do you think git-annex could support [Amazon Glacier](http://aws.amazon.com/glacier/) as a backend?
+"""]]

doc/design/assistant/blog/day_62__smarter_syncing.mdwn

@@ -0,0 +1,21 @@
+Woke up this morning with most of the design for a smarter approach to
+[[syncing]] in my head. (This is why I sometimes slip up and tell people I
+work on this project 12 hours a day..)
+
+To keep the current `assistant` branch working while I make changes
+that break use cases that are working, I've started 
+developing in a new branch, `assistant-wip`.
+
+In it, I've started getting rid of unnecessary expensive transfer scans.
+
+First optimisation I've done is to detect when a remote that was
+disconnected has diverged its `git-annex` branch from the local branch.
+Only when that's the case does a new transfer scan need to be done, to find
+out what new stuff might be available on that remote, to have caused the
+change to its branch, while it was disconnected.
+
+That broke a lot of stuff. I have a plan to fix it written down in
+[[syncing]]. It'll involve keeping track of whether a transfer scan has
+ever been done (if not, one should be run), and recording logs when
+transfers failed, so those failed transfers can be retried when the
+remote gets reconnected.

doc/design/assistant/syncing.mdwn

@@ -3,9 +3,42 @@ all the other git clones, at both the git level and the key/value level.
 
 ## immediate action items
 
-* At startup, and possibly periodically, or when the network connection
+* Optimisations in 5c3e14649ee7c404f86a1b82b648d896762cbbc2 temporarily
-  changes, or some heuristic suggests that a remote was disconnected from
+  broke content syncing in some situations, which need to be added back.
-  us for a while, queue remotes for processing by the TransferScanner.
+
+  Now syncing a disconnected remote only starts a transfer scan if the
+  remote's git-annex branch has diverged, which indicates it probably has
+  new files. But that leaves open the cases where the local repo has
+  new files; and where the two repos git branches are in sync, but the
+  content transfers are lagging behind; and where the transfer scan has
+  never been run.
+
+  Need to track locally whether we're believed to be in sync with a remote.
+  This includes:
+  * All local content has been transferred to it successfully.
+  * The remote has been scanned once for data to transfer from it, and all
+    transfers initiated by that scan succeeded.
+
+  Note the complication that, if it's initiated a transfer, our queued
+  transfer will be thrown out as unnecessary. But if its transfer then
+  fails, that needs to be noticed.
+
+  If we're going to track failed transfers, we could just set a flag,
+  and use that flag later to initiate a new transfer scan. We need a flag
+  in any case, to ensure that a transfer scan is run for each new remote.
+  The flag could be `.git/annex/transfer/scanned/uuid`.
+
+  But, if failed transfers are tracked, we could also record them, in 
+  order to retry them later, without the scan. I'm thinking about a
+  directory like `.git/annex/transfer/failed/{upload,download}/uuid/`,
+  which failed transfer log files could be moved to.
+
+  Note that a remote may lose content it had before, so when requeuing
+  a failed download, should check the location log to see if it still has
+  the content, and if not, queue a download from elsewhere. (And, a remote
+  may get content we were uploading from elsewhere, so check the location
+  log when queuing a failed Upload too.)
+
 * Ensure that when a remote receives content, and updates its location log,
   it syncs that update back out. Prerequisite for:
 * After git sync, identify new content that we don't have that is now available
@@ -43,6 +76,10 @@ all the other git clones, at both the git level and the key/value level.
   that need to be done to sync with a remote. Currently it walks the git
   working copy and checks each file.
 
+## misc todo
+
+* --debug will show often unnecessary work being done. Optimise.
+
 ## data syncing
 
 There are two parts to data syncing. First, map the network and second,
@@ -157,3 +194,5 @@ redone to check it.
   finishes. **done**
 * Test MountWatcher on KDE, and add whatever dbus events KDE emits when
   drives are mounted. **done**
+* It would be nice if, when a USB drive is connected, 
+  syncing starts automatically. Use dbus on Linux? **done**

doc/forum/How_to_define_an_alternative_remote_url_for_a_git_remote_repository__63__/comment_3_48c3a80c14a85f27d742482b2ccbe628._comment

@@ -0,0 +1,8 @@
+[[!comment format=mdwn
+ username="https://me.yahoo.com/speredenn#aaf38"
+ nickname="Jean-Baptiste Carré"
+ subject="comment 3"
+ date="2012-08-21T18:15:48Z"
+ content="""
+You're totally right: The UUIDs are the same. So it shouldn't matter if there are many repositories pointing to the same folder, as you state it. Thanks a lot!
+"""]]