clonebundles: advertise clone bundles feature to clients

Server operators that have enabled clone bundles probably want clients
to use it. This patch introduces a feature that will insert a bundle2
"output" part that advertises the existence of the clone bundles
feature to clients that aren't using it.

The server uses the "cbattempted" argument to "getbundle" to determine
whether a client supports clone bundles and to avoid sending the message
to clients that failed the clone bundle for whatever reason.

hgext/clonebundles.py

@@ -1,98 +1,140
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """server side extension to advertise pre-generated bundles to seed clones.
 
 The extension essentially serves the content of a .hg/clonebundles.manifest
 file to clients that request it.
 
 The clonebundles.manifest file contains a list of URLs and attributes. URLs
 hold pre-generated bundles that a client fetches and applies. After applying
 the pre-generated bundle, the client will connect back to the original server
 and pull data not in the pre-generated bundle.
 
 Manifest File Format:
 
 The manifest file contains a newline (\n) delimited list of entries.
 
 Each line in this file defines an available bundle. Lines have the format:
 
     <URL> [<key>=<value]
 
 That is, a URL followed by extra metadata describing it. Metadata keys and
 values should be URL encoded.
 
 This metadata is optional. It is up to server operators to populate this
 metadata.
 
 Keys in UPPERCASE are reserved for use by Mercurial. All non-uppercase keys
 can be used by site installations.
 
 The server operator is responsible for generating the bundle manifest file.
 
 Metadata Attributes:
 
 BUNDLESPEC
    A "bundle specification" string that describes the type of the bundle.
 
    These are string values that are accepted by the "--type" argument of
    `hg bundle`.
 
    The values are parsed in strict mode, which means they must be of the
    "<compression>-<type>" form. See
    mercurial.exchange.parsebundlespec() for more details.
 
    Clients will automatically filter out specifications that are unknown or
    unsupported so they won't attempt to download something that likely won't
    apply.
 
    The actual value doesn't impact client behavior beyond filtering:
    clients will still sniff the bundle type from the header of downloaded
    files.
 
 REQUIRESNI
    Whether Server Name Indication (SNI) is required to connect to the URL.
    SNI allows servers to use multiple certificates on the same IP. It is
    somewhat common in CDNs and other hosting providers. Older Python
    versions do not support SNI. Defining this attribute enables clients
    with older Python versions to filter this entry.
 
    If this is defined, it is important to advertise a non-SNI fallback
    URL or clients running old Python releases may not be able to clone
    with the clonebundles facility.
 
    Value should be "true".
 """
 
+from mercurial.i18n import _
+from mercurial.node import nullid
 from mercurial import (
+    exchange,
     extensions,
     wireproto,
 )
 
 testedwith = 'internal'
 
 def capabilities(orig, repo, proto):
     caps = orig(repo, proto)
 
     # Only advertise if a manifest exists. This does add some I/O to requests.
     # But this should be cheaper than a wasted network round trip due to
     # missing file.
     if repo.opener.exists('clonebundles.manifest'):
         caps.append('clonebundles')
 
     return caps
 
 @wireproto.wireprotocommand('clonebundles', '')
 def bundles(repo, proto):
     """Server command for returning info for available bundles to seed clones.
 
     Clients will parse this response and determine what bundle to fetch.
 
     Other extensions may wrap this command to filter or dynamically emit
     data depending on the request. e.g. you could advertise URLs for
     the closest data center given the client's IP address.
     """
     return repo.opener.tryread('clonebundles.manifest')
 
[e-mail]2partsgenerator('clonebundlesadvertise', 0)
+def advertiseclonebundlespart(bundler, repo, source, bundlecaps=None,
+                              b2caps=None, heads=None, common=None,
+                              cbattempted=None, **kwargs):
+    """Inserts an output part to advertise clone bundles availability."""
+    # Allow server operators to disable this behavior.
+    # # experimental config: ui.clonebundleadvertise
+    if not repo.ui.configbool('ui', 'clonebundleadvertise', True):
+        return
+
+    # Only advertise if a manifest is present.
+    if not repo.opener.exists('clonebundles.manifest'):
+        return
+
+    # And when changegroup data is requested.
+    if not kwargs.get('cg', True):
+        return
+
+    # And when the client supports clone bundles.
+    if cbattempted is None:
+        return
+
+    # And when the client didn't attempt a clone bundle as part of this pull.
+    if cbattempted:
+        return
+
+    # And when a full clone is requested.
+    # Note: client should not send "cbattempted" for regular pulls. This check
+    # is defense in depth.
+    if common and common != [nullid]:
+        return
+
+    msg = _('this server supports the experimental "clone bundles" feature '
+            'that should enable faster and more reliable cloning\n'
+            'help test it by setting the "experimental.clonebundles" config '
+            'flag to "true"')
+
+    bundler.newpart('output', data=msg)
+
 def extsetup(ui):
     extensions.wrapfunction(wireproto, '_capabilities', capabilities)

tests/test-clonebundles.t

@@ -1,357 +1,368
 Set up a server
 
   $ hg init server
   $ cd server
   $ cat >> .hg/hgrc << EOF
   > [extensions]
   > clonebundles =
   > EOF
 
   $ touch foo
   $ hg -q commit -A -m 'add foo'
   $ touch bar
   $ hg -q commit -A -m 'add bar'
 
   $ hg serve -d -p $HGPORT --pid-file hg.pid --accesslog access.log
   $ cat hg.pid >> $DAEMON_PIDS
   $ cd ..
 
 Feature disabled by default
 (client should not request manifest)
 
   $ hg clone -U http://localhost:$HGPORT feature-disabled
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
 
   $ cat server/access.log
   * - - [*] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
   * - - [*] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D (glob)
   * - - [*] "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bundlecaps=HG20%2Cbundle2%3DHG20%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=1&common=0000000000000000000000000000000000000000&heads=aaff8d2ffbbf07a46dd1f05d8ae7877e3f56e2a2&listkeys=phase%2Cbookmarks (glob)
   * - - [*] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases (glob)
 
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > clonebundles = true
   > EOF
 
 Missing manifest should not result in server lookup
 
   $ hg --verbose clone -U http://localhost:$HGPORT no-manifest
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
 
   $ tail -4 server/access.log
   * - - [*] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
   * - - [*] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D (glob)
   * - - [*] "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bundlecaps=HG20%2Cbundle2%3DHG20%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=1&common=0000000000000000000000000000000000000000&heads=aaff8d2ffbbf07a46dd1f05d8ae7877e3f56e2a2&listkeys=phase%2Cbookmarks (glob)
   * - - [*] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases (glob)
 
 Empty manifest file results in retrieval
 (the extension only checks if the manifest file exists)
 
   $ touch server/.hg/clonebundles.manifest
   $ hg --verbose clone -U http://localhost:$HGPORT empty-manifest
   no clone bundles available on remote; falling back to regular clone
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
 
+Server advertises presence of feature to client requesting full clone
+
+  $ hg --config experimental.clonebundles=false clone -U http://localhost:$HGPORT advertise-on-clone
+  requesting all changes
+  remote: this server supports the experimental "clone bundles" feature that should enable faster and more reliable cloning
+  remote: help test it by setting the "experimental.clonebundles" config flag to "true"
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 2 changes to 2 files
+
 Manifest file with invalid URL aborts
 
   $ echo 'http://does.not.exist/bundle.hg' > server/.hg/clonebundles.manifest
   $ hg clone http://localhost:$HGPORT 404-url
   applying clone bundle from http://does.not.exist/bundle.hg
   error fetching bundle: [Errno -2] Name or service not known
   abort: error applying bundle
   (if this error persists, consider contacting the server operator or disable clone bundles via "--config experimental.clonebundles=false")
   [255]
 
 Server is not running aborts
 
   $ echo "http://localhost:$HGPORT1/bundle.hg" > server/.hg/clonebundles.manifest
   $ hg clone http://localhost:$HGPORT server-not-runner
   applying clone bundle from http://localhost:$HGPORT1/bundle.hg
   error fetching bundle: [Errno 111] Connection refused
   abort: error applying bundle
   (if this error persists, consider contacting the server operator or disable clone bundles via "--config experimental.clonebundles=false")
   [255]
 
 Server returns 404
 
   $ python $TESTDIR/dumbhttp.py -p $HGPORT1 --pid http.pid
   $ cat http.pid >> $DAEMON_PIDS
   $ hg clone http://localhost:$HGPORT running-404
   applying clone bundle from http://localhost:$HGPORT1/bundle.hg
   HTTP error fetching bundle: HTTP Error 404: File not found
   abort: error applying bundle
   (if this error persists, consider contacting the server operator or disable clone bundles via "--config experimental.clonebundles=false")
   [255]
 
 We can override failure to fall back to regular clone
 
   $ hg --config ui.clonebundlefallback=true clone -U http://localhost:$HGPORT 404-fallback
   applying clone bundle from http://localhost:$HGPORT1/bundle.hg
   HTTP error fetching bundle: HTTP Error 404: File not found
   falling back to normal clone
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
 
 Bundle with partial content works
 
   $ hg -R server bundle --type gzip-v1 --base null -r 53245c60e682 partial.hg
   1 changesets found
 
 We verify exact bundle content as an extra check against accidental future
 changes. If this output changes, we could break old clients.
 
   $ f --size --hexdump partial.hg
   partial.hg: size=208
   0000: 48 47 31 30 47 5a 78 9c 63 60 60 98 17 ac 12 93 |HG10GZx.c``.....|
   0010: f0 ac a9 23 45 70 cb bf 0d 5f 59 4e 4a 7f 79 21 |...#Ep..._YNJ.y!|
   0020: 9b cc 40 24 20 a0 d7 ce 2c d1 38 25 cd 24 25 d5 |..@$ ...,.8%.$%.|
   0030: d8 c2 22 cd 38 d9 24 cd 22 d5 c8 22 cd 24 cd 32 |..".8.$."..".$.2|
   0040: d1 c2 d0 c4 c8 d2 32 d1 38 39 29 c9 34 cd d4 80 |......2.89).4...|
   0050: ab 24 b5 b8 84 cb 40 c1 80 2b 2d 3f 9f 8b 2b 31 |.$....@..+-?..+1|
   0060: 25 45 01 c8 80 9a d2 9b 65 fb e5 9e 45 bf 8d 7f |%E......e...E...|
   0070: 9f c6 97 9f 2b 44 34 67 d9 ec 8e 0f a0 92 0b 75 |....+D4g.......u|
   0080: 41 d6 24 59 18 a4 a4 9a a6 18 1a 5b 98 9b 5a 98 |A.$Y.......[..Z.|
   0090: 9a 18 26 9b a6 19 98 1a 99 99 26 a6 18 9a 98 24 |..&.......&....$|
   00a0: 26 59 a6 25 5a 98 a5 18 a6 24 71 41 35 b1 43 dc |&Y.%Z....$qA5.C.|
   00b0: 96 b0 83 f7 e9 45 8b d2 56 c7 a3 1f 82 52 d7 8a |.....E..V....R..|
   00c0: 78 ed fc d5 76 f1 36 95 dc 05 07 00 ad 39 5e d3 |x...v.6......9^.|
 
   $ echo "http://localhost:$HGPORT1/partial.hg" > server/.hg/clonebundles.manifest
   $ hg clone -U http://localhost:$HGPORT partial-bundle
   applying clone bundle from http://localhost:$HGPORT1/partial.hg
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
   finished applying clone bundle
   searching for changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
 
 Bundle with full content works
 
   $ hg -R server bundle --type gzip-v2 --base null -r tip full.hg
   2 changesets found
 
 Again, we perform an extra check against bundle content changes. If this content
 changes, clone bundles produced by new Mercurial versions may not be readable
 by old clients.
 
   $ f --size --hexdump full.hg
   full.hg: size=408
   0000: 48 47 32 30 00 00 00 0e 43 6f 6d 70 72 65 73 73 |HG20....Compress|
   0010: 69 6f 6e 3d 47 5a 78 9c 63 60 60 90 e5 76 f6 70 |ion=GZx.c``..v.p|
   0020: f4 73 77 75 0f f2 0f 0d 60 00 02 46 06 76 a6 b2 |.swu....`..F.v..|
   0030: d4 a2 e2 cc fc 3c 03 23 06 06 e6 7d 40 b1 4d c1 |.....<.#...}@.M.|
   0040: 2a 31 09 cf 9a 3a 52 04 b7 fc db f0 95 e5 a4 f4 |*1...:R.........|
   0050: 97 17 b2 c9 0c 14 00 02 e6 d9 99 25 1a a7 a4 99 |...........%....|
   0060: a4 a4 1a 5b 58 a4 19 27 9b a4 59 a4 1a 59 a4 99 |...[X..'..Y..Y..|
   0070: a4 59 26 5a 18 9a 18 59 5a 26 1a 27 27 25 99 a6 |.Y&Z...YZ&.''%..|
   0080: 99 1a 70 95 a4 16 97 70 19 28 18 70 a5 e5 e7 73 |..p....p.(.p...s|
   0090: 71 25 a6 a4 28 00 19 40 13 0e ac fa df ab ff 7b |q%..(..@.......{|
   00a0: 3f fb 92 dc 8b 1f 62 bb 9e b7 d7 d9 87 3d 5a 44 |?.....b......=ZD|
   00b0: ac 2f b0 a9 c3 66 1e 54 b9 26 08 a7 1a 1b 1a a7 |./...f.T.&......|
   00c0: 25 1b 9a 1b 99 19 9a 5a 18 9b a6 18 19 00 dd 67 |%......Z.......g|
   00d0: 61 61 98 06 f4 80 49 4a 8a 65 52 92 41 9a 81 81 |aa....IJ.eR.A...|
   00e0: a5 11 17 50 31 30 58 19 cc 80 98 25 29 b1 08 c4 |...P10X....%)...|
   00f0: 37 07 79 19 88 d9 41 ee 07 8a 41 cd 5d 98 65 fb |7.y...A...A.].e.|
   0100: e5 9e 45 bf 8d 7f 9f c6 97 9f 2b 44 34 67 d9 ec |..E.......+D4g..|
   0110: 8e 0f a0 61 a8 eb 82 82 2e c9 c2 20 25 d5 34 c5 |...a....... %.4.|
   0120: d0 d8 c2 dc d4 c2 d4 c4 30 d9 34 cd c0 d4 c8 cc |........0.4.....|
   0130: 34 31 c5 d0 c4 24 31 c9 32 2d d1 c2 2c c5 30 25 |41...$1.2-..,.0%|
   0140: 09 e4 ee 85 8f 85 ff 88 ab 89 36 c7 2a c4 47 34 |..........6.*.G4|
   0150: fe f8 ec 7b 73 37 3f c3 24 62 1d 8d 4d 1d 9e 40 |...{s7?.$b..M..@|
   0160: 06 3b 10 14 36 a4 38 10 04 d8 21 01 5a b2 83 f7 |.;..6.8...!.Z...|
   0170: e9 45 8b d2 56 c7 a3 1f 82 52 d7 8a 78 ed fc d5 |.E..V....R..x...|
   0180: 76 f1 36 25 81 49 c0 ad 30 c0 0e 49 8f 54 b7 9e |v.6%.I..0..I.T..|
   0190: d4 1c 09 00 bb 8d f0 bd                         |........|
 
   $ echo "http://localhost:$HGPORT1/full.hg" > server/.hg/clonebundles.manifest
   $ hg clone -U http://localhost:$HGPORT full-bundle
   applying clone bundle from http://localhost:$HGPORT1/full.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Entry with unknown BUNDLESPEC is filtered and not used
 
   $ cat > server/.hg/clonebundles.manifest << EOF
   > http://bad.entry1 BUNDLESPEC=UNKNOWN
   > http://bad.entry2 BUNDLESPEC=xz-v1
   > http://bad.entry3 BUNDLESPEC=none-v100
   > http://localhost:$HGPORT1/full.hg BUNDLESPEC=gzip-v2
   > EOF
 
   $ hg clone -U http://localhost:$HGPORT filter-unknown-type
   applying clone bundle from http://localhost:$HGPORT1/full.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Automatic fallback when all entries are filtered
 
   $ cat > server/.hg/clonebundles.manifest << EOF
   > http://bad.entry BUNDLESPEC=UNKNOWN
   > EOF
 
   $ hg clone -U http://localhost:$HGPORT filter-all
   no compatible clone bundles available on server; falling back to regular clone
   (you may want to report this to the server operator)
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
 
 URLs requiring SNI are filtered in Python <2.7.9
 
   $ cp full.hg sni.hg
   $ cat > server/.hg/clonebundles.manifest << EOF
   > http://localhost:$HGPORT1/sni.hg REQUIRESNI=true
   > http://localhost:$HGPORT1/full.hg
   > EOF
 
 #if sslcontext
 Python 2.7.9+ support SNI
 
   $ hg clone -U http://localhost:$HGPORT sni-supported
   applying clone bundle from http://localhost:$HGPORT1/sni.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 #else
 Python <2.7.9 will filter SNI URLs
 
   $ hg clone -U http://localhost:$HGPORT sni-unsupported
   applying clone bundle from http://localhost:$HGPORT1/full.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 #endif
 
 Set up manifest for testing preferences
 (Remember, the TYPE does not have to match reality - the URL is
 important)
 
   $ cp full.hg gz-a.hg
   $ cp full.hg gz-b.hg
   $ cp full.hg bz2-a.hg
   $ cp full.hg bz2-b.hg
   $ cat > server/.hg/clonebundles.manifest << EOF
   > http://localhost:$HGPORT1/gz-a.hg BUNDLESPEC=gzip-v2 extra=a
   > http://localhost:$HGPORT1/bz2-a.hg BUNDLESPEC=bzip2-v2 extra=a
   > http://localhost:$HGPORT1/gz-b.hg BUNDLESPEC=gzip-v2 extra=b
   > http://localhost:$HGPORT1/bz2-b.hg BUNDLESPEC=bzip2-v2 extra=b
   > EOF
 
 Preferring an undefined attribute will take first entry
 
   $ hg --config experimental.clonebundleprefers=foo=bar clone -U http://localhost:$HGPORT prefer-foo
   applying clone bundle from http://localhost:$HGPORT1/gz-a.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Preferring bz2 type will download first entry of that type
 
   $ hg --config experimental.clonebundleprefers=COMPRESSION=bzip2 clone -U http://localhost:$HGPORT prefer-bz
   applying clone bundle from http://localhost:$HGPORT1/bz2-a.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Preferring multiple values of an option works
 
   $ hg --config experimental.clonebundleprefers=COMPRESSION=unknown,COMPRESSION=bzip2 clone -U http://localhost:$HGPORT prefer-multiple-bz
   applying clone bundle from http://localhost:$HGPORT1/bz2-a.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Sorting multiple values should get us back to original first entry
 
   $ hg --config experimental.clonebundleprefers=BUNDLESPEC=unknown,BUNDLESPEC=gzip-v2,BUNDLESPEC=bzip2-v2 clone -U http://localhost:$HGPORT prefer-multiple-gz
   applying clone bundle from http://localhost:$HGPORT1/gz-a.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Preferring multiple attributes has correct order
 
   $ hg --config experimental.clonebundleprefers=extra=b,BUNDLESPEC=bzip2-v2 clone -U http://localhost:$HGPORT prefer-separate-attributes
   applying clone bundle from http://localhost:$HGPORT1/bz2-b.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found
 
 Test where attribute is missing from some entries
 
   $ cat > server/.hg/clonebundles.manifest << EOF
   > http://localhost:$HGPORT1/gz-a.hg BUNDLESPEC=gzip-v2
   > http://localhost:$HGPORT1/bz2-a.hg BUNDLESPEC=bzip2-v2
   > http://localhost:$HGPORT1/gz-b.hg BUNDLESPEC=gzip-v2 extra=b
   > http://localhost:$HGPORT1/bz2-b.hg BUNDLESPEC=bzip2-v2 extra=b
   > EOF
 
   $ hg --config experimental.clonebundleprefers=extra=b clone -U http://localhost:$HGPORT prefer-partially-defined-attribute
   applying clone bundle from http://localhost:$HGPORT1/gz-b.hg
   adding changesets
   adding manifests
   adding file changes
   added 2 changesets with 2 changes to 2 files
   finished applying clone bundle
   searching for changes
   no changes found