also:

- DataTid -> DataTidHint + 0 if there is no such hint.

So now we are benchmarking disk for sizes 4K and 2M which are the usual
sizes popping up with e.g. wendelin.core.

* origin/master:
  client: account for cache hit/miss statistics
  client: remove redundant information from cache's __repr__
  cache: fix possible endless loop in __repr__/_iterQueue
  storage: speed up replication by not getting object next_serial for nothing
  storage: speed up replication by sending bigger network packets
  neoctl: remove ignored option
  client: bug found, add log to collect more information
  client: new 'cache-size' Storage option
  doc: mention HTTPS URLs when possible
  doc: update comment in neolog about Python issue 13773
  neolog: add support for xz-compressed logs, using external xzcat commands
  neolog: --from option now also tries to parse with dateutil
  importer: do not crash if a backup cluster tries to replicate
  storage: disable data deduplication by default
  Release version 1.8.1

This information is handy to see how well cache performs.

Amended by Julien Muchembled:
- do not abbreviate some existing field names in repr result (asking the
  user to look at the source code in order to decipher logs is not nice)
- hit: change from %.1f to %.3g
- hit: hide it completely if nload is 0
- use __future__.division instead of adding more casts to float

On my disk it gives:

name                                 time/op
deco/disk/randread/direct/4K-min     98.0µs ± 1%
deco/disk/randread/direct/4K-avg      104µs ± 0%
deco/disk/randread/direct/1M-min     2.90ms ±17%
deco/disk/randread/direct/1M-avg     3.55ms ± 0%
deco/disk/randread/pagecache/4K-min   227ns ± 1%
deco/disk/randread/pagecache/4K-avg   629ns ± 0%
deco/disk/randread/pagecache/1M-min  70.8µs ± 7%
deco/disk/randread/pagecache/1M-avg  99.4µs ± 1%

INFO Z2 Log files reopened successfully
INFO SignalHandler Caught signal SIGTERM
INFO Z2 Shutting down fast
INFO ZServer closing HTTP to new connections
ERROR ZODB.Connection Couldn't load state for BTrees.LOBTree.LOBucket 0xc12e29
Traceback (most recent call last):
  File "ZODB/Connection.py", line 909, in setstate
    self._setstate(obj, oid)
  File "ZODB/Connection.py", line 953, in _setstate
    p, serial = self._storage.load(oid, '')
  File "neo/client/Storage.py", line 81, in load
    return self.app.load(oid)[:2]
  File "neo/client/app.py", line 355, in load
    data, tid, next_tid, _ = self._loadFromStorage(oid, tid, before_tid)
  File "neo/client/app.py", line 387, in _loadFromStorage
    askStorage)
  File "neo/client/app.py", line 297, in _askStorageForRead
    self.sync()
  File "neo/client/app.py", line 898, in sync
    self._askPrimary(Packets.Ping())
  File "neo/client/app.py", line 163, in _askPrimary
    return self._ask(self._getMasterConnection(), packet,
  File "neo/client/app.py", line 177, in _getMasterConnection
    result = self.master_conn = self._connectToPrimaryNode()
  File "neo/client/app.py", line 202, in _connectToPrimaryNode
    index = (index + 1) % len(master_list)
ZeroDivisionError: integer division or modulo by zero

It's not possible yet to replicate a node that is importing data.
One must wait that the migration is finished.

This would prevent e.g. eth1 going before eth0 as it was the case in 55a64368.

; NEO/py log to no-log:
$ ./benchstat-neopy-lognolog 20171106-time-rio-Cenabled.txt
name                                    old µs/object  new µs/object  delta
dataset:wczblk1-8
rio/neo/py/sqlite/zhash.py                   304 ± 6%       291 ± 2%     ~     (p=0.056 n=5+5)
rio/neo/py/sqlite/zhash.py-P16             2.19k ± 0%     2.01k ± 2%   -8.20%  (p=0.000 n=13+16)
rio/neo/py/sqlite/zhash.go                   248 ± 1%       231 ± 1%   -7.19%  (p=0.008 n=5+5)
rio/neo/py/sqlite/zhash.go+prefetch128       125 ± 1%       110 ± 2%  -11.57%  (p=0.008 n=5+5)
rio/neo/py/sqlite/zhash.go-P16             1.76k ±13%     1.62k ± 7%   -8.06%  (p=0.015 n=16+16)
rio/neo/py/sql/zhash.py                      325 ± 4%       313 ± 4%     ~     (p=0.114 n=4+4)
rio/neo/py/sql/zhash.py-P16                2.88k ± 1%     2.56k ± 1%  -11.05%  (p=0.000 n=15+15)
rio/neo/py/sql/zhash.go                      275 ± 2%       258 ± 1%   -6.03%  (p=0.008 n=5+5)
rio/neo/py/sql/zhash.go+prefetch128          154 ± 3%       139 ± 1%   -9.29%  (p=0.008 n=5+5)
rio/neo/py/sql/zhash.go-P16                2.30k ± 8%     2.21k ± 5%     ~     (p=0.072 n=16+16)
dataset:prod1-1024
rio/neo/py/sqlite/zhash.py                   269 ± 1%       259 ± 4%   -3.49%  (p=0.032 n=5+5)
rio/neo/py/sqlite/zhash.py-P16             2.19k ± 0%     1.89k ± 1%  -13.62%  (p=0.000 n=16+15)
rio/neo/py/sqlite/zhash.go                   158 ± 1%       142 ± 1%  -10.36%  (p=0.008 n=5+5)
rio/neo/py/sqlite/zhash.go+prefetch128       116 ± 3%       101 ± 2%  -13.22%  (p=0.008 n=5+5)
rio/neo/py/sqlite/zhash.go-P16             1.90k ± 0%     1.57k ± 0%  -17.14%  (p=0.000 n=14+13)
rio/neo/py/sql/zhash.py                      337 ±43%       293 ± 4%     ~     (p=0.286 n=5+4)
rio/neo/py/sql/zhash.py-P16                2.73k ± 0%     2.47k ± 0%   -9.45%  (p=0.000 n=15+15)
rio/neo/py/sql/zhash.go                      186 ± 3%       168 ± 1%   -9.39%  (p=0.008 n=5+5)
rio/neo/py/sql/zhash.go+prefetch128          145 ± 2%       130 ± 2%  -10.24%  (p=0.008 n=5+5)
rio/neo/py/sql/zhash.go-P16                2.29k ± 6%     2.08k ± 3%   -9.20%  (p=0.000 n=16+16)

--------

; Full summary
$ benchstat -split dataset 20171106-time-rio-Cenabled.txt
name                                          pystone/s
rio/pystone                                    178k ± 2%

name                                          µs/op
rio/sha1/py/1024B                              1.40 ± 0%
rio/sha1/go/1024B                              1.79 ± 1%
rio/sha1/py/4096B                              5.08 ± 2%
rio/sha1/go/4096B                              7.14 ± 0%

name                                          us/op
rio/disk/randread/direct/4K-min                34.0 ± 1%
rio/disk/randread/direct/4K-avg                92.9 ± 0%

name                                          time/op
rio/disk/randread/pagecache/4K-min            221ns ± 0%
rio/disk/randread/pagecache/4K-avg            637ns ± 0%

name                                          µs/object
dataset:wczblk1-8
rio/fs1/zhash.py                               22.3 ± 2%
rio/fs1/zhash.py-P16                           51.7 ±72%
rio/fs1/zhash.go                               2.40 ± 0%
rio/fs1/zhash.go+prefetch128                   4.34 ± 8%
rio/fs1/zhash.go-P16                           3.58 ±24%
rio/zeo/zhash.py                                336 ± 2%
rio/zeo/zhash.py-P16                          1.61k ±19%
rio/neo/py/sqlite/zhash.py                      304 ± 6%
rio/neo/py/sqlite/zhash.py-P16                2.19k ± 0%
rio/neo/py/sqlite/zhash.go                      248 ± 1%
rio/neo/py/sqlite/zhash.go+prefetch128          125 ± 1%
rio/neo/py/sqlite/zhash.go-P16                1.76k ±13%
rio/neo/py(!log)/sqlite/zhash.py                291 ± 2%
rio/neo/py(!log)/sqlite/zhash.py-P16          2.01k ± 2%
rio/neo/py(!log)/sqlite/zhash.go                231 ± 1%
rio/neo/py(!log)/sqlite/zhash.go+prefetch128    110 ± 2%
rio/neo/py(!log)/sqlite/zhash.go-P16          1.62k ± 7%
rio/neo/py/sql/zhash.py                         325 ± 4%
rio/neo/py/sql/zhash.py-P16                   2.88k ± 1%
rio/neo/py/sql/zhash.go                         275 ± 2%
rio/neo/py/sql/zhash.go+prefetch128             154 ± 3%
rio/neo/py/sql/zhash.go-P16                   2.30k ± 8%
rio/neo/py(!log)/sql/zhash.py                   313 ± 4%
rio/neo/py(!log)/sql/zhash.py-P16             2.56k ± 1%
rio/neo/py(!log)/sql/zhash.go                   258 ± 1%
rio/neo/py(!log)/sql/zhash.go+prefetch128       139 ± 1%
rio/neo/py(!log)/sql/zhash.go-P16             2.21k ± 5%
rio/neo/go/zhash.py                             190 ± 3%
rio/neo/go/zhash.py-P16                         784 ± 9%
rio/neo/go/zhash.go                            52.0 ± 1%
rio/neo/go/zhash.go+prefetch128                26.6 ± 5%
rio/neo/go/zhash.go-P16                         256 ± 6%
rio/neo/go(!sha1)/zhash.go                     35.3 ± 4%
rio/neo/go(!sha1)/zhash.go+prefetch128         17.3 ± 2%
rio/neo/go(!sha1)/zhash.go-P16                  152 ±13%
dataset:prod1-1024
rio/fs1/zhash.py                               18.9 ± 1%
rio/fs1/zhash.py-P16                           58.0 ±52%
rio/fs1/zhash.go                               1.30 ± 0%
rio/fs1/zhash.go+prefetch128                   2.78 ±14%
rio/fs1/zhash.go-P16                           2.21 ± 9%
rio/zeo/zhash.py                                302 ± 7%
rio/zeo/zhash.py-P16                          1.44k ±11%
rio/neo/py/sqlite/zhash.py                      269 ± 1%
rio/neo/py/sqlite/zhash.py-P16                2.19k ± 0%
rio/neo/py/sqlite/zhash.go                      158 ± 1%
rio/neo/py/sqlite/zhash.go+prefetch128          116 ± 3%
rio/neo/py/sqlite/zhash.go-P16                1.90k ± 0%
rio/neo/py(!log)/sqlite/zhash.py                259 ± 4%
rio/neo/py(!log)/sqlite/zhash.py-P16          1.89k ± 1%
rio/neo/py(!log)/sqlite/zhash.go                142 ± 1%
rio/neo/py(!log)/sqlite/zhash.go+prefetch128    101 ± 2%
rio/neo/py(!log)/sqlite/zhash.go-P16          1.57k ± 0%
rio/neo/py/sql/zhash.py                         337 ±43%
rio/neo/py/sql/zhash.py-P16                   2.73k ± 0%
rio/neo/py/sql/zhash.go                         186 ± 3%
rio/neo/py/sql/zhash.go+prefetch128             145 ± 2%
rio/neo/py/sql/zhash.go-P16                   2.29k ± 6%
rio/neo/py(!log)/sql/zhash.py                   293 ± 4%
rio/neo/py(!log)/sql/zhash.py-P16             2.47k ± 0%
rio/neo/py(!log)/sql/zhash.go                   168 ± 1%
rio/neo/py(!log)/sql/zhash.go+prefetch128       130 ± 2%
rio/neo/py(!log)/sql/zhash.go-P16             2.08k ± 3%
rio/neo/go/zhash.py                             181 ± 5%
rio/neo/go/zhash.py-P16                         714 ± 6%
rio/neo/go/zhash.go                            36.9 ± 3%
rio/neo/go/zhash.go+prefetch128                16.5 ± 1%
rio/neo/go/zhash.go-P16                         239 ± 4%
rio/neo/go(!sha1)/zhash.go                     32.7 ± 7%
rio/neo/go(!sha1)/zhash.go+prefetch128         13.5 ± 1%
rio/neo/go(!sha1)/zhash.go-P16                  190 ± 7%