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Kirill Smelkov
neo
Commits
5fc83902
Commit
5fc83902
authored
Mar 20, 2021
by
Kirill Smelkov
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parent
8ee4675a
Changes
2
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2 changed files
with
67 additions
and
23 deletions
+67
-23
go/zodb/storage/demo/demo.go
go/zodb/storage/demo/demo.go
+66
-22
go/zodb/storage/demo/demo_test.go
go/zodb/storage/demo/demo_test.go
+1
-1
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go/zodb/storage/demo/demo.go
View file @
5fc83902
...
...
@@ -30,6 +30,7 @@ import (
"io"
"net/url"
"regexp"
"sync"
"lab.nexedi.com/kirr/go123/mem"
"lab.nexedi.com/kirr/go123/xerr"
...
...
@@ -54,6 +55,10 @@ type Storage struct {
watchWG
*
xsync
.
WorkGroup
watchCancel
func
()
downOnce
sync
.
Once
down
chan
struct
{}
// ready when storage is down
downErr
error
// reason for shutdown
}
// baseMutatedError is reported when Storage.base is detected to change.
...
...
@@ -78,6 +83,7 @@ func (e *baseError) Error() string {
func
(
e
*
baseError
)
Cause
()
error
{
return
e
.
err
}
func
(
e
*
baseError
)
Unwrap
()
error
{
return
e
.
err
}
// watcher detects base mutation and proxies δ events to user watchq.
// it runs as separate goroutine.
func
(
d
*
Storage
)
watcher
(
ctx
context
.
Context
)
error
{
...
...
@@ -111,11 +117,11 @@ func (d *Storage) watcher(ctx context.Context) error {
edown
=
fmt
.
Errorf
(
"base: unexpected event %T"
,
event
)
}
d
.
shutdown
(
edown
)
ev
:=
&
zodb
.
EventError
{
edown
}
// XXX + context
if
d
.
watchq
!=
nil
{
d
.
watchq
<-
ev
}
// XXX d.shutdown(edown)
return
edown
// event on δ -> proxy to user
...
...
@@ -132,6 +138,15 @@ func (d *Storage) watcher(ctx context.Context) error {
}
}
// shutdown marks Storage as no longer being operational due to reason.
func
(
d
*
Storage
)
shutdown
(
reason
error
)
{
d
.
downOnce
.
Do
(
func
()
{
d
.
downErr
=
reason
close
(
d
.
down
)
})
}
var
errClosed
=
errors
.
New
(
"storage is closed"
)
// Close implements zodb.IStorageDriver .
func
(
d
*
Storage
)
Close
()
(
err
error
)
{
...
...
@@ -141,6 +156,7 @@ func (d *Storage) Close() (err error) {
}
}()
d
.
shutdown
(
errClosed
)
errδ
:=
d
.
δ
.
Close
()
errBase
:=
d
.
base
.
Close
()
...
...
@@ -200,38 +216,51 @@ func (d *Storage) Load(ctx context.Context, xid zodb.Xid) (_ *mem.Buf, _ zodb.Ti
}
}()
data
,
serial
,
err
:=
d
.
δ
.
Load
(
ctx
,
xid
)
if
err
==
nil
{
// object data is present in δ
return
data
,
serial
,
nil
if
ready
(
d
.
down
)
{
return
nil
,
zodb
.
InvalidTid
,
d
.
downErr
}
useBase
:=
false
inδ
:=
false
var
eNoData
*
zodb
.
NoDataError
var
eNoObject
*
zodb
.
NoObjectError
switch
{
case
errors
.
As
(
err
,
&
eNoData
)
:
if
eNoData
.
DeletedAt
!=
0
{
// object deleted in δ -> whiteout
return
data
,
serial
,
eNoData
}
else
{
// object present in δ but not yet created as of xid.at
inδ
:=
false
if
xid
.
At
>
d
.
baseAt0
{
data
,
serial
,
err
:=
d
.
δ
.
Load
(
ctx
,
xid
)
if
err
==
nil
{
// object data is present in δ
return
data
,
serial
,
nil
}
useBase
:=
false
switch
{
case
errors
.
As
(
err
,
&
eNoData
)
:
if
eNoData
.
DeletedAt
!=
0
{
// object deleted in δ -> whiteout
return
data
,
serial
,
eNoData
}
else
{
// object present in δ but not yet created as of xid.at
useBase
=
true
inδ
=
true
}
case
errors
.
As
(
err
,
&
eNoObject
)
:
// object not created in δ
useBase
=
true
inδ
=
true
}
case
errors
.
As
(
err
,
&
eNoObject
)
:
// object not created in δ
useBase
=
true
if
!
useBase
{
return
data
,
serial
,
err
}
}
if
!
useBase
{
return
data
,
serial
,
err
// cap .at in xid to .baseAt0 (we convert it back on error return, and
// it makes more robust wrt simultaneous base mutation).
xidBase
:=
xid
if
xid
.
At
>
d
.
baseAt0
{
xidBase
.
At
=
d
.
baseAt0
}
// XXX cap .at in xid to .baseAt0 ? (and convert back on error return)
data
,
serial
,
err
=
d
.
base
.
Load
(
ctx
,
xid
)
data
,
serial
,
err
:=
d
.
base
.
Load
(
ctx
,
xidBase
)
if
err
==
nil
{
return
data
,
serial
,
nil
}
...
...
@@ -350,6 +379,8 @@ func openByURL(ctx context.Context, u *url.URL, opt *zodb.DriverOptions) (_ zodb
baseWatchq
:
baseWatchq
,
δWatchq
:
δWatchq
,
watchq
:
opt
.
Watchq
,
down
:
make
(
chan
struct
{}),
}
// spawn watcher to listen on baseWatchq and shutdown storage if base changes.
...
...
@@ -364,3 +395,16 @@ func openByURL(ctx context.Context, u *url.URL, opt *zodb.DriverOptions) (_ zodb
func
init
()
{
zodb
.
RegisterDriver
(
"demo"
,
openByURL
)
}
// misc
// ready returns whether c is ready.
func
ready
(
c
<-
chan
struct
{})
bool
{
select
{
case
<-
c
:
return
true
default
:
return
false
}
}
go/zodb/storage/demo/demo_test.go
View file @
5fc83902
...
...
@@ -240,7 +240,7 @@ func TestWatchLoad_vs_BaseMutate(t *testing.T) {
t
.
Fatalf
(
"after base mutate: load: unexpected error:
\n
have: %s
\n
want: %s"
,
err
,
errOk
)
}
if
!
(
data
==
nil
&&
serial
==
0
)
{
if
!
(
data
==
nil
&&
serial
==
zodb
.
InvalidTid
)
{
t
.
Fatalf
(
"after base mutate: load: unexpected data=%v serial=%v"
,
data
,
serial
)
}
})
...
...
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