* export: exports the newest data checkpoint. It forces a checkpoint before
exporting (currently no wals are exported)
* import: cleans up etcd, creates a new datasnaphot from the provided import stream
and then initializes etcd. Currently no old data is removed from the object
storage but it's just ignored.
Since we are using the shared cache with the lock notify we won't receive
SQLITE_BUSY errors but we could receive SQLITE_LOCKED errors due to deadlocks or
locked tables on concurrent read and write transactions.
This patch catches this kind of errors and retries the tx until maxTxRetries.
In runservice readdb Run method we could end with a deadlock if two of the
goroutines that call HandleEvents.* try to write to the errCh at the same
time before the errCh is read. If this happens one of the two will be blocked on
writing to the channel but the read won't happen since it'll blocked by
wg.Wait().
Fix this doing:
* use a buffered channel large as the number of executed goroutines.
* create a new errCh at every loop (so we'll ignore later errors after the first
one)
Note: we could also use a non blocking send to avoid this situation but we
should also start the wg.Wait before the goroutines or earlier errors could be
lost causing another kind of hang.
When doing an initEtcd (new instance or etcd reset) create a new wal (that will
have a new sequence epoch) and do a checkpoint.
In this way:
* readdb will detect that an epoch change and do a full resync
* we always have a data file (also if empty) that provides the last checkpointed
wal. This information could be used by readdb to resync
* Don't make cors enabled on all (*) by default.
* Handle related web.allowedOrigins options
* Only the gateway api should be called by a browser so setup the cors handler
only on it
currently we are deleting the executor tasks only when all the run tasks
log/archives were fetched. But it'll better to remove a single executor task
when the task fetching is finished.
This could also fix possible issues on k8s since we are scheduling tasks but the
k8s scheduler may not schedule them if there aren't enough resources causing a
scheduling deadlock since we won't remove finished pods because their related
tasks are not removed and k8s cannot start new pods since it has no resources.
Before kubernetes 1.14 nodes were labeled with the "beta.kubernetes.io/arch"
label instead of the "kubernetes.io/arch".
Current k8s version (v1.15) labels nodes with both labels but it's
deprecated and will removed in future versions.
At driver start get the current k8s api version and choose the right label to
use as node selector based on it.
