global numcopies setting

* numcopies: New command, sets global numcopies value that is seen by all
  clones of a repository.
* The annex.numcopies git config setting is deprecated. Once the numcopies
  command is used to set the global number of copies, any annex.numcopies
  git configs will be ignored.
* assistant: Make the prefs page set the global numcopies.

This global numcopies setting is needed to let preferred content
expressions operate on numcopies.

It's also convenient, because typically if you want git-annex to preserve N
copies of files in a repo, you want it to do that no matter which repo it's
running in. Making it global avoids needing to warn the user about gotchas
involving inconsistent annex.numcopies settings.
(See changes to doc/numcopies.mdwn.)

Added a new variety of git-annex branch log file, that holds only 1 value.
Will probably be useful for other stuff later.

This commit was sponsored by Nicolas Pouillard.

7 files changed, 45 insertions, 27 deletions

diff --git a/doc/copies.mdwn b/doc/copies.mdwn
index 93cbd8ea8..205d2d5b1 100644
--- a/doc/copies.mdwn
+++ b/doc/copies.mdwn
@@ -6,8 +6,8 @@ command.  So, git-annex can be configured to try
 to keep N copies of a file's content available across all repositories. 
 (Although [[untrusted_repositories|trust]] don't count toward this total.)
 
-By default, N is 1; it is configured by annex.numcopies. This default
-can be overridden on a per-file-type basis by the annex.numcopies
+By default, N is 1; it is configured by running `git annex numcopies N`.
+This default can be overridden on a per-file-type basis by the annex.numcopies
 setting in `.gitattributes` files. The --numcopies switch allows
 temporarily using a different value.
 
@@ -30,9 +30,3 @@ refuse to do so.
 
 With N=2, in order to drop the file content from Laptop, it would need access
 to both USB and Server.
-
-Note that different repositories can be configured with different values of
-N. So just because Laptop has N=2, this does not prevent the number of
-copies falling to 1, when USB and Server have N=1. To avoid this,
-configure it in `.gitattributes`, which is shared between repositories
-using git.
diff --git a/doc/git-annex.mdwn b/doc/git-annex.mdwn
index e8058720c..4e7bd2395 100644
--- a/doc/git-annex.mdwn
+++ b/doc/git-annex.mdwn
@@ -403,6 +403,20 @@ subdirectories).
   keyid+= and keyid-= with such remotes should be used with care, and
   make little sense except in cases like the revoked key example above.
 
+* `numcopies [N]`
+
+  Tells git-annex how many copies it should preserve of files, over all
+  repositories. The default is 1.
+
+  Run without a number to get the current value.
+
+  When git-annex is asked to drop a file, it first verifies that the
+  required number of copies can be satisfied amoung all the other
+  repositories that have a copy of the file.
+
+  This can be overridden on a per-file basis by the annex.numcopies setting
+  in .gitattributes files.
+
 * `trust [repository ...]`
 
   Records that a repository is trusted to not unexpectedly lose
@@ -828,7 +842,7 @@ subdirectories).
 * `--auto`
 
   Enable automatic mode. Commands that get, drop, or move file contents
-  will only do so when needed to help satisfy the setting of annex.numcopies,
+  will only do so when needed to help satisfy the setting of numcopies,
   and preferred content configuration.
 
 * `--all`
@@ -883,7 +897,7 @@ subdirectories).
 
 * `--numcopies=n`
 
-  Overrides the `annex.numcopies` setting, forcing git-annex to ensure the
+  Overrides the numcopies setting, forcing git-annex to ensure the
   specified number of copies exist.
 
   Note that setting numcopies to 0 is very unsafe.
@@ -1117,12 +1131,6 @@ Here are all the supported configuration settings.
 
   A unique UUID for this repository (automatically set).
 
-* `annex.numcopies`
-
-  Number of copies of files to keep across all repositories. (default: 1)
-
-  Note that setting numcopies to 0 is very unsafe.
-
 * `annex.backends`
 
   Space-separated list of names of the key-value backends to use.
@@ -1151,6 +1159,17 @@ Here are all the supported configuration settings.
 
         	annex.largefiles = largerthan=100kb and not (include=*.c or include=*.h)
 
+* `annex.numcopies`
+
+  This is a deprecated setting. You should instead use the
+  `git annex numcopies` command to configure how many copies of files
+  are kept acros all repositories.
+
+  This config setting is only looked at when `git annex numcopies` has
+  never been configured.
+
+  Note that setting numcopies to 0 is very unsafe.
+
 * `annex.queuesize`
 
   git-annex builds a queue of git commands, in order to combine similar
@@ -1456,10 +1475,12 @@ but the SHA256E backend for ogg files:
 
 The numcopies setting can also be configured on a per-file-type basis via
 the `annex.numcopies` attribute in `.gitattributes` files. This overrides
-any value set using `annex.numcopies` in `.git/config`.
-For example, this makes two copies be needed for wav files:
+other numcopies settings.
+For example, this makes two copies be needed for wav files and 3 copies
+for flac files:
 
 	*.wav annex.numcopies=2
+	*.flac annex.numcopies=3
 
 Note that setting numcopies to 0 is very unsafe.
 
diff --git a/doc/internals.mdwn b/doc/internals.mdwn
index d95ab3f5e..1cf0cf505 100644
--- a/doc/internals.mdwn
+++ b/doc/internals.mdwn
@@ -56,8 +56,11 @@ space and then the description, followed by a timestamp. Example:
 	e605dca6-446a-11e0-8b2a-002170d25c55 laptop timestamp=1317929189.157237s
 	26339d22-446b-11e0-9101-002170d25c55 usb disk timestamp=1317929330.769997s
 
-If there are multiple lines for the same uuid, the one with the most recent
-timestamp wins. git-annex union merges this and other files.
+## `numcopies.log`
+
+Records the global numcopies setting.
+
+The file format is simply a timestamp followed by a number.
 
 ## `remote.log`
 
diff --git a/doc/tips/using_the_web_as_a_special_remote.mdwn b/doc/tips/using_the_web_as_a_special_remote.mdwn
index 706ae2951..62ef58b69 100644
--- a/doc/tips/using_the_web_as_a_special_remote.mdwn
+++ b/doc/tips/using_the_web_as_a_special_remote.mdwn
@@ -34,7 +34,7 @@ With the result that it will hang onto files:
 	  Could only verify the existence of 0 out of 1 necessary copies
 	  Also these untrusted repositories may contain the file:
 	  	00000000-0000-0000-0000-000000000001  -- web
-	  (Use --force to override this check, or adjust annex.numcopies.)
+	  (Use --force to override this check, or adjust numcopies.)
 	failed
 
 ## attaching urls to existing files
diff --git a/doc/todo/preferred_content_numcopies_check.mdwn b/doc/todo/preferred_content_numcopies_check.mdwn
index 956888cca..066f02cfb 100644
--- a/doc/todo/preferred_content_numcopies_check.mdwn
+++ b/doc/todo/preferred_content_numcopies_check.mdwn
@@ -47,10 +47,10 @@ work tree, which gitattributes settings do not.
 Conclusion:
 
 * Add to the git-annex branch a numcopies file that holds the global
-  numcopies default if present.
-* Modify the assistant to use it when configuring numcopies.
+  numcopies default if present. **done**
+* Modify the assistant to use it when configuring numcopies. **done**
 * To deprecate .git/config's annex.numcopies, only make it take effect
-  when there is no numcopies file in the git-annex branch.
+  when there is no numcopies file in the git-annex branch. **done**
 * Add "numcopiesneeded=N" preferred content expression using the git-annex
   branch numcopies setting, overridden by any .gitattributes numcopies setting
   for a particular file. It should ignore the other ways to specify
diff --git a/doc/walkthrough/fsck:_verifying_your_data.mdwn b/doc/walkthrough/fsck:_verifying_your_data.mdwn
index d036332fb..62e15b6fa 100644
--- a/doc/walkthrough/fsck:_verifying_your_data.mdwn
+++ b/doc/walkthrough/fsck:_verifying_your_data.mdwn
@@ -2,7 +2,7 @@ You can use the fsck subcommand to check for problems in your data. What
 can be checked depends on the key-value [[backend|backends]] you've used
 for the data. For example, when you use the SHA1 backend, fsck will verify
 that the checksums of your files are good. Fsck also checks that the
-annex.numcopies setting is satisfied for all files.
+[[numcopies|copies]] setting is satisfied for all files.
 
 	# git annex fsck
 	fsck some_file (checksum...) ok
diff --git a/doc/walkthrough/removing_files:_When_things_go_wrong.mdwn b/doc/walkthrough/removing_files:_When_things_go_wrong.mdwn
index 2d3c0cde0..ccd2d197f 100644
--- a/doc/walkthrough/removing_files:_When_things_go_wrong.mdwn
+++ b/doc/walkthrough/removing_files:_When_things_go_wrong.mdwn
@@ -10,12 +10,12 @@ you'll see something like this.
 	  Try making some of these repositories available:
 	   	58d84e8a-d9ae-11df-a1aa-ab9aa8c00826  -- portable USB drive
 	   	ca20064c-dbb5-11df-b2fe-002170d25c55  -- backup SATA drive
-	  (Use --force to override this check, or adjust annex.numcopies.)
+	  (Use --force to override this check, or adjust numcopies.)
 	failed
 	drop other.iso (unsafe)
 	  Could only verify the existence of 0 out of 1 necessary copies
           No other repository is known to contain the file.
-	  (Use --force to override this check, or adjust annex.numcopies.)
+	  (Use --force to override this check, or adjust numcopies.)
 	failed
 
 Here you might --force it to drop `important_file` if you [[trust]] your backup.