This modifies the read window aggregate interfaces to future-proof it
if and when we add additional capabilities to the method. Previously,
the interface was all or nothing. If we modified the RPC call itself, we
would have to make a new interface to denote the change to the Go code.
This changes the interface so now a `WindowAggregateCapability` exists.
This way, we can modify the struct to include things like:
```
type WindowAggregateCapability struct {
WindowPeriodCapability bool
MeanAggregateCapability bool
}
```
This way we can learn if the RPC call itself supports some specific
option. If the first iteration doesn't support a mean aggregate or the
mean aggregate is only supported by single server implementations, the
window aggregate can tell the caller that it won't be able to compute
the mean aggregate.
Since it fills in a struct with these capabilities, the struct can
safely introduce new values. If a downstream consumer wants to take
advantage of that functionality, then all interfaces in the chain have
to be updated to consume the upstream capabilities.
The `ReadWindowAggregateSource` will invoke the `ReadWindowAggregate`
method on the `influxdb.Reader` and return the table. It is implemented
using the same common methods that are used for the other sources.
Added an interface for an additional storage capability. This interface
will allow for checking if the reader supports the window aggregate call
and another method for invoking the call if it does.
This is implemented using a single interface. If the reader implements
the interface, it indicates that the client is capable of reading the
response. The `HasXXX` method is intended to check if the store supports
the operation. This method also takes a context because it could require
a remote call or to wait for one.
This updates the semantic graph usage to accomodate the change to the
semantic graph that removed the ambiguity of the body so now it is
always a block instead of being a block or an expression.
The storage filters are modified to use the predicates directly so we do
not have to pass `semantic.FunctionExpression` around. Instead, since
simple expressions are all that are supported anyway, we transform
suitable function expressions into predicates as part of the push down
rule and this simplifies the influxdb reader code.
This also moves the storage predicate conversion code into the standard
library package as it is the only location that uses this code now that
the predicate conversion is done as part of the push down rule.
This refactor was prompted by another refactor of the
`semantic.FunctionExpression` that would cause it to always contain a
`semantic.Block`. Since the push down filter needs the expressions and
to combine them, this refactor allows us not do construct a combined
filter inside of blocks which allows us to have better type safety.
The prometheus project doesn't adhere to the module suffix so any
attempt to use it as a library fails with go 1.13 or greater. The
workaround is to `go get` a specific commit revision that corresponds to
a tag and let go figure out a pseudo-version for it.
In this case, I updated the revision to the one pointed at by `v2.9.2`
since that is what the current `go.mod` file pointed at. I also updated
the go version to 1.13 inside of `go.mod` to be the same as influxdb.
See https://github.com/prometheus/prometheus/issues/6048 for details.
I think it is a nice utility function that I would like to use
elsewhere.
So I decided to move it out to the tracing package.
Signed-off-by: Gianluca Arbezzano <gianarb92@gmail.com>
jlapacik
Yiqun Zhang
Johnny Steenbergen
Jonathan A. Sternberg
Paul Hummer
Alirie Gray
Gianluca Arbezzano
Lorenzo Affetti
Gianluca Arbezzano
Christopher M. Wolff