* master:
  go/zodb/zeo: Fix initialization when server database is empty
  neotest: info-local: Fix NIC display for virtio devices
  neotest: info-local: Fix it when CPU frequence/idle information is not available

In that case at0 was initialized as 0 and still considered uninitialized
by flushEventq0:

    (neo) (z-dev) (g.env) kirr@deco:~/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo$ go test -run Empty
    ------
    2020-10-12T07:39:25 INFO ZEO.runzeo (146240) opening storage '1' using FileStorage
    ------
    2020-10-12T07:39:25 INFO ZEO.StorageServer StorageServer created RW with storages: 1:RW:/tmp/zeo905263273/1.fs
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.server listening on /tmp/zeo905263273/1.fs.zeosock
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.base Connected server protocol
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.server received handshake 'Z5'
    2020/10/12 07:39:25 /tmp/zeo905263273/1.fs.zeosock: EOF
    --- FAIL: TestEmptyDB (0.22s)
        --- FAIL: TestEmptyDB/py/msgpack=false (0.22s)
    panic: flush, but .at0 not yet initialized [recovered]
            panic: flush, but .at0 not yet initialized

    goroutine 7 [running]:
    testing.tRunner.func1.1(0x644a60, 0x6e1a50)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1072 +0x30d
    testing.tRunner.func1(0xc000001e00)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1075 +0x41a
    panic(0x644a60, 0x6e1a50)
            /home/kirr/src/tools/go/go/src/runtime/panic.go:969 +0x175
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.(*zeo).flushEventq0(0xc00018a000)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo.go:180 +0xf3
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.openByURL(0x6e9ca0, 0xc000016108, 0xc000138120, 0xc000153d98, 0x0, 0x0, 0x0, 0x0, 0x0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo.go:488 +0x5ba
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.zeoOpen(0xc000018740, 0x1e, 0xc000049d98, 0x0, 0x0, 0x0, 0x0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:285 +0x17b
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEO.func1(0xc000001e00, 0x6e9ea0, 0xc00005e6c0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:219 +0xd0
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func2.1(0xc0000185c0, 0x16)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:205 +0xfb
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func1(0xc000001e00, 0xc00000e5a0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:185 +0x129
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func2(0xc000001e00)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:197 +0x105
    testing.tRunner(0xc000001e00, 0xc00000e440)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1123 +0xef
    created by testing.(*T).Run
            /home/kirr/src/tools/go/go/src/testing/testing.go:1168 +0x2b3
    exit status 2
    FAIL    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo     0.227s

-> Fix it by using dedicated field marking whether .at0 was initialized or not yet.

In that case at0 was initialized as 0 and still considered uninitialized
by flushEventq0:

    (neo) (z-dev) (g.env) kirr@deco:~/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo$ go test -run Empty
    ------
    2020-10-12T07:39:25 INFO ZEO.runzeo (146240) opening storage '1' using FileStorage
    ------
    2020-10-12T07:39:25 INFO ZEO.StorageServer StorageServer created RW with storages: 1:RW:/tmp/zeo905263273/1.fs
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.server listening on /tmp/zeo905263273/1.fs.zeosock
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.base Connected server protocol
    ------
    2020-10-12T07:39:25 INFO ZEO.asyncio.server received handshake 'Z5'
    2020/10/12 07:39:25 /tmp/zeo905263273/1.fs.zeosock: EOF
    --- FAIL: TestEmptyDB (0.22s)
        --- FAIL: TestEmptyDB/py/msgpack=false (0.22s)
    panic: flush, but .at0 not yet initialized [recovered]
            panic: flush, but .at0 not yet initialized

    goroutine 7 [running]:
    testing.tRunner.func1.1(0x644a60, 0x6e1a50)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1072 +0x30d
    testing.tRunner.func1(0xc000001e00)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1075 +0x41a
    panic(0x644a60, 0x6e1a50)
            /home/kirr/src/tools/go/go/src/runtime/panic.go:969 +0x175
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.(*zeo).flushEventq0(0xc00018a000)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo.go:180 +0xf3
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.openByURL(0x6e9ca0, 0xc000016108, 0xc000138120, 0xc000153d98, 0x0, 0x0, 0x0, 0x0, 0x0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo.go:488 +0x5ba
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.zeoOpen(0xc000018740, 0x1e, 0xc000049d98, 0x0, 0x0, 0x0, 0x0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:285 +0x17b
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEO.func1(0xc000001e00, 0x6e9ea0, 0xc00005e6c0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:219 +0xd0
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func2.1(0xc0000185c0, 0x16)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:205 +0xfb
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func1(0xc000001e00, 0xc00000e5a0)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:185 +0x129
    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo.withZEOSrv.func2(0xc000001e00)
            /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/storage/zeo/zeo_test.go:197 +0x105
    testing.tRunner(0xc000001e00, 0xc00000e440)
            /home/kirr/src/tools/go/go/src/testing/testing.go:1123 +0xef
    created by testing.(*T).Run
            /home/kirr/src/tools/go/go/src/testing/testing.go:1168 +0x2b3
    exit status 2
    FAIL    lab.nexedi.com/kirr/neo/go/zodb/storage/zeo     0.227s

-> Fix it by using dedicated field marking whether .at0 was initialized or not yet.

For virtio NICs /sys/class/net/<NIC>/device lead to $pcidev/virtioX, not just $pcidev, e.g.:

	$ realpath /sys/class/net/ens3/device
	/sys/devices/pci0000:00/0000:00:03.0/virtio0

and we were extracting virtio0 instead of 0000:00:03.0 as PCI device identifier.

-> Fix it by recognizing and stripping /virtioX suffix.

For example under KVM it was failing as

    cpu:	Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq: No such file or directory
      File "<string>", line 1
        print '%.2fGHz' % ( / 1E6)
                            ^
    SyntaxError: invalid syntax

    $ lscpu
    Architecture:        x86_64
    CPU op-mode(s):      32-bit, 64-bit
    Byte Order:          Little Endian
    Address sizes:       40 bits physical, 48 bits virtual
    CPU(s):              40
    On-line CPU(s) list: 0-39
    Thread(s) per core:  1
    Core(s) per socket:  1
    Socket(s):           40
    NUMA node(s):        1
    Vendor ID:           GenuineIntel
    CPU family:          6
    Model:               63
    Model name:          Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    Stepping:            2
    CPU MHz:             2494.238
    BogoMIPS:            4988.47
    Virtualization:      VT-x
    Hypervisor vendor:   KVM
    Virtualization type: full
    L1d cache:           32K
    L1i cache:           32K
    L2 cache:            4096K
    L3 cache:            16384K
    NUMA node0 CPU(s):   0-39
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat

-> Fix it by checking whether cpufreq/cpuidle directories are available, and display "?" if they are not.

For virtio NICs /sys/class/net/<NIC>/device lead to $pcidev/virtioX, not just $pcidev, e.g.:

	$ realpath /sys/class/net/ens3/device
	/sys/devices/pci0000:00/0000:00:03.0/virtio0

and we were extracting virtio0 instead of 0000:00:03.0 as PCI device identifier.

-> Fix it by recognizing and stripping /virtioX suffix.

For example under KVM it was failing as

    cpu:	Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq: No such file or directory
      File "<string>", line 1
        print '%.2fGHz' % ( / 1E6)
                            ^
    SyntaxError: invalid syntax

    $ lscpu
    Architecture:        x86_64
    CPU op-mode(s):      32-bit, 64-bit
    Byte Order:          Little Endian
    Address sizes:       40 bits physical, 48 bits virtual
    CPU(s):              40
    On-line CPU(s) list: 0-39
    Thread(s) per core:  1
    Core(s) per socket:  1
    Socket(s):           40
    NUMA node(s):        1
    Vendor ID:           GenuineIntel
    CPU family:          6
    Model:               63
    Model name:          Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    Stepping:            2
    CPU MHz:             2494.238
    BogoMIPS:            4988.47
    Virtualization:      VT-x
    Hypervisor vendor:   KVM
    Virtualization type: full
    L1d cache:           32K
    L1i cache:           32K
    L2 cache:            4096K
    L3 cache:            16384K
    NUMA node0 CPU(s):   0-39
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat

-> Fix it by checking whether cpufreq/cpuidle directories are available, and display "?" if they are not.

* master:
  go/neo/neonet: Don't avoid defer anymore
  go/zodb/fs1: Don't avoid defer anymore

Starting from Go1.14 defer is no longer slow:
https://golang.org/doc/go1.14#runtime

Starting from Go1.14 defer is no longer slow:
https://golang.org/doc/go1.14#runtime

* master: (31 commits)
  go/zodb/zeo: Make "no serial on load after object deleted" to be a known bug
  go/zodb/zeo: Cosmetics
  go/zodb/zeo: Load: Fix thinko when rejecting result
  go/zodb/zeo: Add support for invalidations
  go/zodb/zeo: Teach zlink to serve incoming notification and requests
  go/zodb/zeo: MsgPack support
  go/zodb/zeo: Accept both int|bool for pickled message flags
  go/zodb/zeo: Factor-out tuple handling into encoding
  go/zodb/zeo: Factor-out string|bytes handling into encoding
  go/zodb/zeo: proto: Use enc.<X> and enc.as<X> to encode/decode type X
  go/zodb/zeo: Introduce notion of encoding
  go/zodb/zeo: Factor-out code to prepare pkt from message into pktEncode
  go/zodb/zeo: Start moving things related to protocol and messages encoding into proto.go
  go/zodb/zeo: Shutdown zlink on first error
  go/zodb/zeo: Use zlink as term for link in between peers
  go/zodb/zeo: Don't avoid defer
  go/zodb/zeo: errgroup -> xsync.WorkGroup
  go/zodb/zeo: Initial tests
  go/zodb/zeo: Fix thinko in openByURL error context
  go/internal/xtesting: LoadDBHistory
  ...

This turns zeo tests to pass.
The bug is reported upstream here: https://github.com/zopefoundation/ZODB/issues/318

This turns zeo tests to pass.
The bug is reported upstream here: https://github.com/zopefoundation/ZODB/issues/318

If xres fails to convert to tuple, we should error about xres, not res
which is always tuple(nil).

Receive invalidation from server and send corresponding events to watchq.
Care to send only events with tid > at0 that we initially returned when opening.

Tests pass, but they need https://github.com/zopefoundation/ZEO/pull/160

This will be used in the next patch to handle invalidateTransaction
messages.

ZEO5 adds way for messages to be encoded via either pickles or MessagePack.
However until now we were always using pickles.
Let's add msgpack support to be able to e.g. use wire encoding that
server prefers.

MsgPack support is almost fully localized in encoding.
We use tinylib/msgp runtime routines to decode/encode msg fields with known types,
and shamaton/msgpack to decode/encode msg.arg, which is interface{},
because msgp does not generally work for arbitrary reflections.

For msgpack=true, tests state is the same as with pickles: handshake
works, but load fails when verifying that Load returns correct error for
deleted object:

    TestLoad/py/msgpack=false: xtesting.go:272: load 0285cbacc06d3a4c:0000000000000007: returned err unexpected:
        have: /tmp/zeo170183943/1.fs.zeosock: load 0285cbacc06d3a4c:0000000000000007: 0000000000000007: no such object
        want: /tmp/zeo170183943/1.fs.zeosock: load 0285cbacc06d3a4c:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c
    TestLoad/py/msgpack=false: xtesting.go:272: load 0285cbad858bf2e6:0000000000000006: returned err unexpected:
        have: /tmp/zeo170183943/1.fs.zeosock: load 0285cbad858bf2e6:0000000000000006: 0000000000000006: no such object
        want: /tmp/zeo170183943/1.fs.zeosock: load 0285cbad858bf2e6:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6
    TestLoad/py/msgpack=false: xtesting.go:290: load 7fffffffffffffff:0000000000000007: returned err unexpected:
        have: /tmp/zeo170183943/1.fs.zeosock: load 7fffffffffffffff:0000000000000007: 0000000000000007: no such object
        want: /tmp/zeo170183943/1.fs.zeosock: load 7fffffffffffffff:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c
    TestLoad/py/msgpack=false: xtesting.go:290: load 7fffffffffffffff:0000000000000006: returned err unexpected:
        have: /tmp/zeo170183943/1.fs.zeosock: load 7fffffffffffffff:0000000000000006: 0000000000000006: no such object
        want: /tmp/zeo170183943/1.fs.zeosock: load 7fffffffffffffff:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6

    TestLoad/py/msgpack=true: xtesting.go:272: load 0285cbacc06d3a4c:0000000000000007: returned err unexpected:
        have: /tmp/zeo247652538/1.fs.zeosock: load 0285cbacc06d3a4c:0000000000000007: 0000000000000007: no such object
        want: /tmp/zeo247652538/1.fs.zeosock: load 0285cbacc06d3a4c:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c
    TestLoad/py/msgpack=true: xtesting.go:272: load 0285cbad858bf2e6:0000000000000006: returned err unexpected:
        have: /tmp/zeo247652538/1.fs.zeosock: load 0285cbad858bf2e6:0000000000000006: 0000000000000006: no such object
        want: /tmp/zeo247652538/1.fs.zeosock: load 0285cbad858bf2e6:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6
    TestLoad/py/msgpack=true: xtesting.go:290: load 7fffffffffffffff:0000000000000007: returned err unexpected:
        have: /tmp/zeo247652538/1.fs.zeosock: load 7fffffffffffffff:0000000000000007: 0000000000000007: no such object
        want: /tmp/zeo247652538/1.fs.zeosock: load 7fffffffffffffff:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c
    TestLoad/py/msgpack=true: xtesting.go:290: load 7fffffffffffffff:0000000000000006: returned err unexpected:
        have: /tmp/zeo247652538/1.fs.zeosock: load 7fffffffffffffff:0000000000000006: 0000000000000006: no such object
        want: /tmp/zeo247652538/1.fs.zeosock: load 7fffffffffffffff:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6

This is due to https://github.com/zopefoundation/ZODB/issues/318