glusterd: Improvements to peer identification

This patch improves the peer identification mechanism in glusterd and
lays down the framework for further improvements, including better multi
network support in glusterd.

This patch mainly does two things,
1. Extend the peerinfo object to store a list of addresses instead of a
single hostname as it does now. This also includes changes to make the
peer update behaviour of 'peer probe' to add to the list.

2. Improve glusterd_friend_find_by_hostname() to perform better matching
of hostnames. glusterd_friend_find_by_hostname() now does and initial
quick string compare against all the peer addresses known to glusterd,
after which it tries a more thorough search using address resolution and
matching the struc sockaddr's.

The above two changes together improve the peer identification situation
in glusterd a lot.

More information regarding the problem this patch attempts to resolve
and the approach chosen can be found at
http://www.gluster.org/community/documentation/index.php/Features/Better_peer_identification

This commit is a squashed commit of the following changes, the
development branch of which can be viewed at,
https://github.com/kshlm/glusterfs/tree/better-peer-identification or,
https://forge.gluster.org/~kshlm/glusterfs-core/kshlms-glusterfs/commits/better-peer-identification

commit 198f86e60fab74faf082eaa02657a4d8f60b92f0
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 15 14:34:06 2014 +0530

    Update gluster.8

commit 35d597f3a6b3248373e727f7b7e889c92554d56c
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 15 09:01:01 2014 +0530

    Address review comments

    https://review.gluster.org/#/c/8238/3

commit 47b5331e17304477322bd2daed5bbed503c34ca1
Merge: c71b12c 78128af
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 15 08:41:39 2014 +0530

    Merge branch 'master' into better-peer-identification

commit c71b12c164330e8d19d1df4734ab34ef9a8caad2
Merge: 57bc9de 0f5719a
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jul 10 19:50:19 2014 +0530

    Merge branch 'master' into better-peer-identification

commit 57bc9de9e4f49ff2b1620df9906cda50a3527a25
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jul 10 19:49:08 2014 +0530

    More fixes to review comments

commit 5482cc363a687a9e246a0780ec88acd53e218501
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jul 10 18:36:40 2014 +0530

    Code refactoring in peer-utils based on review comments

    https://review.gluster.org/#/c/8238/2/xlators/mgmt/glusterd/src/glusterd-peer-utils.c

commit 89b22c34757178f64d5fbaffa31e6302f841c060
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jul 10 12:30:00 2014 +0530

    Hostnames in peer status

commit 63ebf9485cf50d736cf640238a1ab241671fcaf1
Merge: c8c8fdd f5f9721
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jul 10 12:06:33 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit c8c8fdd2104b5b6b8a1af739b1dd952b74e6dd66
Author: Kaushal M <kaushal@redhat.com>
Date:   Wed Jul 9 18:35:27 2014 +0530

    Hostnames in xml output

commit 732a92a0167ad7b1d70edbc35ebd8307c2766ae1
Author: Kaushal M <kaushal@redhat.com>
Date:   Wed Jul 9 15:12:10 2014 +0530

    Add hostnames to cli rsp dict during list-friends

commit fcf43e3e317508f0c225024738a988a4af8e9205
Merge: c0e2624 72d96e2
Author: Kaushal M <kaushal@redhat.com>
Date:   Wed Jul 9 12:53:03 2014 +0530

    Merge branch 'master' into better-peer-identification

commit c0e262416728a3c536a8347a216e471eb2251535
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 16:11:19 2014 +0530

    Use list_for_each_entry_safe when cleaning peer hostnames

commit 6132e60224eb592f3657e535a12a3e72c772da42
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 15:52:19 2014 +0530

    Fix crash in gd_add_friend_to_dict

commit 88ffa9a508fd5aac0b2a76e6e76487ce0cab786a
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 13:19:44 2014 +0530

    gd_peerinfo_destroy -> glusterd_peerinfo_destroy

commit 4b36930a715b1e13cd1a77d136ef1cf78a06d574
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 12:50:12 2014 +0530

    More refactoring

commit ee559b081d608c6501c10ae22166f26eeb65690e
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 12:14:40 2014 +0530

    Major refactoring of code based on review comments at
    https://review.gluster.org/#/c/8238/1/xlators/mgmt/glusterd/src/glusterd-peer-utils.h

commit e96dbc7bbb05fad2a9c424de41a394b8023fe48d
Merge: 2613d1d 83c09b7
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jul 7 09:47:05 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit 2613d1daebff0c56812de821c06ed4c16bb9d447
Merge: b242cf6 9a50211
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 15:28:57 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit b242cf66d95dd3dd5e3975aa430baa6bd74b8a29
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 15:08:18 2014 +0530

    Fix a silly mistake, if (ctx->req) => if (ctx->req == NULL)

commit c835ed26433830ceed57289143f596cf60421558
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 14:58:23 2014 +0530

    Fix reverse probe.

commit 9ede17f9329b854b02e8ad159f173244789fd08c
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 13:31:32 2014 +0530

    Fix friend import for existing peers

commit 891bf74c7350064dfb008d1b7294bcec28d680fd
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 13:08:36 2014 +0530

    Set first hostname in peerinfo->hostnames to peerinfo->hostname

commit 9421d6a217381a7427a7d84f369280883ca4297a
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 12:21:40 2014 +0530

    Fix gf_asprintf return val check in glusterd_store_peer_write

commit defac978c1d94011ce8195e311839b9ffce057e7
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 11:16:13 2014 +0530

    Fix store_retrieve_peers to correctly cleanup.

commit 00a799f5de1121b0cb7421da8285f9407063e1bd
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 10:52:11 2014 +0530

    Update address list in glusterd_probe_cbk only when needed.

commit 7a628e8a9c562d85709c69cfa13fb1774c521b75
Merge: d191985 dc46d5e
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri Jul 4 09:24:12 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit d1919858e6639d2b54d716a61f662d9752ec5ff1
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 18:59:49 2014 +0530

    gf_compare_addrinfo -> gf_compare_sockaddr

commit 31d8ef730d408f8d9ba8f504fa648f7dcd59da87
Merge: 93bbede 86ee233
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 18:16:13 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit 93bbedeac5181e29f59b2acd08f638146812ec41
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 18:15:16 2014 +0530

    Improve glusterd_friend_find_by_hostname

    glusterd_friend_find_by_hostname will now do an initial quick search for
    the peerinfo performing string comparisions on the given host string. It
    follows it with a more thorough match, by resolving the addresses and
    comparing addrinfos instead of strings.

commit 2542cdbc45aa9cfcaf1f174686158d5565cdd07b
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 17:21:10 2014 +0530

    New utility gf_compare_addrinfo

commit 338676e8389a44bd91136eebd110197429c2566c
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 14:55:56 2014 +0530

    Use gd_peer_has_address instead of strcmp

commit 28d45be51f594328741c44455bd80ac9d64ca501
Merge: 728266e 991dd5e
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 14:54:40 2014 +0530

    Merge branch 'master' into better-peer-identification

commit 728266eb16d5f5a4bf36266044425ae164337f99
Merge: 7d9b87b 2417de9
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue Jul 1 09:55:13 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit 7d9b87b84955ec17daeaf88a3e7462914039430f
Merge: b890625 e02275c
Author: Kaushal M <kshlmster@gmail.com>
Date:   Tue Jul 1 08:41:40 2014 +0530

    Merge pull request #4 from vpshastry/better-peer-identification

    Better peer identification

commit e02275c52fb83c72ad082c098fd3e432c2b9c526
Merge: 75ee90d b890625
Author: Varun Shastry <vshastry@redhat.com>
Date:   Mon Jun 30 16:44:29 2014 +0530

    Merge branch 'better-peer-identification' of https://github.com/kshlm/glusterfs into better-peer-identification-kaushal-github

commit 75ee90d2f272e49b94d24c9ca4571e89a83055ff
Author: Varun Shastry <vshastry@redhat.com>
Date:   Mon Jun 30 15:36:10 2014 +0530

    glusterd: add to the list if the probed uuid pre-exists

    Signed-off-by: Varun Shastry <vshastry@redhat.com>

commit b890625d8164c660695daef3285c67979eef723e
Merge: 04c5d60 187a7a9
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jun 30 11:44:13 2014 +0530

    Merge remote-tracking branch 'origin/master' into better-peer-identification

commit 04c5d60cb938c8d94b214689580b40abb1b0ffcd
Merge: 3a5bfa1 e01edb6
Author: Kaushal M <kshlmster@gmail.com>
Date:   Sat Jun 28 19:23:33 2014 +0530

    Merge pull request #3 from vpshastry/better-peer-identification

    glusterd: search through the list of hostnames in the peerinfo

commit 0c64f3346a977f9165ac55a84a1e03c40a7573a7
Merge: e01edb6 3a5bfa1
Author: Varun Shastry <vshastry@redhat.com>
Date:   Sat Jun 28 10:43:29 2014 +0530

    Merge branch 'better-peer-identification' of https://github.com/kshlm/glusterfs into better-peer-identification-kaushal-github

commit e01edb63153a1008db70b8fa76ae5b535e099326
Author: Varun Shastry <vshastry@redhat.com>
Date:   Fri Jun 27 12:29:36 2014 +0530

    glusterd: search through the list of hostnames in the peerinfo

    Signed-off-by: Varun Shastry <vshastry@redhat.com>

commit 3a5bfa15855e660db2bfde644727371dd2d618cc
Merge: cda6d31 371ea35
Author: Kaushal M <kshlmster@gmail.com>
Date:   Fri Jun 27 11:31:17 2014 +0530

    Merge pull request #1 from vpshastry/better-peer-identification

    glusterd: Add hostname to list instead of replaceing upon update

commit 371ea354f198b4182382d5403c5960c0b2add6b6
Author: Varun Shastry <vshastry@redhat.com>
Date:   Fri Jun 27 11:24:54 2014 +0530

    glusterd: Add hostname to list instead of replaceing upon update

    Signed-off-by: Varun Shastry <vshastry@redhat.com>

commit cda6d3152886623ecbf46baf0048ebe0119b30b6
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jun 26 19:52:52 2014 +0530

    Import address lists

commit 6649b54aa0440130c08e827e0a1d1bbfb840eca9
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jun 26 19:15:37 2014 +0530

    Implement export address list

commit 55990034eead92bc9b936240029e460a4bf152d5
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jun 26 18:11:59 2014 +0530

    Use first address in list to when setting up the peer RPC.

commit a35fde8d19b9988eb04c652fb3a5e4f84d90ad00
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jun 26 18:03:04 2014 +0530

    Properly free addresses on glusterd_peer_destroy

commit 1988081db09ac9205f3dc7268cef8be267f3ce8b
Author: Kaushal M <kaushal@redhat.com>
Date:   Thu Jun 26 17:52:35 2014 +0530

    Restore peerinfo with address list implemented.

commit 66f524d5749a12f4910dd6b06c9d91f37e1d831e
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon Jun 23 13:02:23 2014 +0530

    Move out all peer related utilities from glusterd-utils to glusterd-peer-utils

commit 14a2a326a4dff11b55490dca2a14f39320931340
Author: Kaushal M <kaushal@redhat.com>
Date:   Tue May 27 12:16:41 2014 +0530

    Compilation fix

commit c59cd351d0a102d0d5f3ea9001fd33c4edcb262f
Author: Kaushal M <kaushal@redhat.com>
Date:   Mon May 5 12:51:11 2014 +0530

    Add store support for hostname list

commit b70325f0beb884ad12645ef40185f0bf6cedd741
Author: Kaushal M <kaushal@redhat.com>
Date:   Fri May 2 15:58:07 2014 +0530

    Add a hostnames list to glusterd_peerinfo_t

    glusterd_peerinfo_new will now init this list and add the given hostname
    as the lists first member.

Signed-off-by: Kaushal M <kaushal@redhat.com>
Signed-off-by: Varun Shastry <vshastry@redhat.com>
Change-Id: Ief3c5d6d6f16571ee2fab0a45e638b9d6506a06e
BUG: 1119547
Reviewed-on: http://review.gluster.org/8238
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>