Retries in restic try to solve two main problems:
- retry a temporarily failed operation
- tolerate temporary network interruptions
The first problem only requires a few retries, whereas the last one benefits
primarily from spreading the requests over a longer duration.
Increasing the default multiplier and the initial interval works for
both cases. The first few retries only take a few seconds, while later
retries quickly reach the maximum interval of one minute. This ensures
that the total number of retries issued by restic will remain at around
21 retries for a 15 minute period. As the concurrency in restic is
bounded, retries drastically reduce the number of requests sent to a
backend. This helps to prevent overloading the backend.
Previously, if an operation failed after 15 minutes, then it would never
be retried. This means that large backend requests are more unreliable
than smaller ones.
Depending on how long an operation takes to fail, the total retry
duration can currently vary between 1.5 and 15 minutes. In particular
for temporarily interrupted network connections, the former timeout is
too short. Thus always use a limit of 15 minutes.
LoadRaw also includes improved context cancellation handling similar to the
implementation in repository.LoadUnpacked.
The removed cache backend test will be added again later on.
If a file exhausts its retry attempts, then it is likely not accessible
the next time. Thus, immediately fail all load calls for that file to
avoid useless retries.
If client.Do returns an error, then there's no body that has to be
closed. For requests for which we are not interested in the response
body, immediately drain and close the body to make sure it isn't
forgotten later on.
This change in particular adds the missing `Close()` call for the
`List()` command.
rclone returns a "not found" error if an internal error occurs while
listing a folder. Ignoring this error lets restic erroneously think that
there are no files, which can cause `prune` to wipe the whole
repository.
This removes code that is only used within a backend implementation from
the backend package. The latter now only contains code that also has
external users.
Allow setting custom arguments for the `sftp` backend, by using the
`sftp.args` option. This is similar to the approach already implemented
in the `rclone` backend, to support new arguments without requiring
future code changes for each different SSH argument.
Closes#4241
The test uses `WithTimeout` to create a context that cancels the List
operation after a given delay. Several backends internally use a derived
child context created using WithCancel.
The cancellation of a context first closes the done channel of the
context (here: the `WithTimeout` context) and _afterwards_ propagates
the cancellation to child contexts (here: the `WithCancel` context).
Therefor if the List implementation uses a child context, then it may
take a moment until that context is also cancelled. Thus give the
context cancellation a moment to propagate.
When transferring a repository from S3 to, for example, a local disk
then all empty folders will be missing.
When saving files, the missing intermediate folders are created
automatically. Therefore, missing directories can be ignored by the
`List()` operation.
Conceptually the backend configuration should be validated when creating
or opening the backend, but not when filling in information from
environment variables into the configuration.
This unified construction removes most backend-specific code from
global.go. The backend registry will also enable integration tests to
use custom backends if necessary.
In order to change the backend initialization in `global.go` to be able
to generically call cfg.ApplyEnvironment() for supported backends, the
`interface{}` returned by `ParseConfig` must contain a pointer to the
configuration.
An alternative would be to use reflection to convert the type from
`interface{}(Config)` to `interface{}(*Config)` (from value to pointer
type). However, this would just complicate the type mess further.
This function casts its argument to int32 before passing it to the
system call, so that big-endian CPUs read the lower rather than the
upper 32 bits of the pid.
This also gets rid of the last import of "unsafe" in the Unix build.
I changed syscall to x/sys/unix while I was at it, to remove one more
import line. The constants and types there are aliases for their syscall
counterparts.
