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## Description Closes: #9404 --- ### Author Checklist *All items are required. Please add a note to the item if the item is not applicable and please add links to any relevant follow up issues.* I have... - [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title - [ ] added `!` to the type prefix if API or client breaking change - [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting)) - [x] provided a link to the relevant issue or specification - [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules) - [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing) - [ ] added a changelog entry to `CHANGELOG.md` - [ ] included comments for [documenting Go code](https://blog.golang.org/godoc) - [ ] updated the relevant documentation or specification - [x] reviewed "Files changed" and left comments if necessary - [x] confirmed all CI checks have passed ### Reviewers Checklist *All items are required. Please add a note if the item is not applicable and please add your handle next to the items reviewed if you only reviewed selected items.* I have... - [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title - [ ] confirmed `!` in the type prefix if API or client breaking change - [ ] confirmed all author checklist items have been addressed - [ ] reviewed state machine logic - [ ] reviewed API design and naming - [ ] reviewed documentation is accurate - [ ] reviewed tests and test coverage - [ ] manually tested (if applicable) |
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README.md | ||
constructor.go | ||
constructor_test.go |
README.md
State Streaming Service
This package contains the constructors for the StreamingService
s used to write state changes out from individual KVStores to a
file or stream, as described in ADR-038 and defined in types/streaming.go.
The child directories contain the implementations for specific output destinations.
Currently, a StreamingService
implementation that writes state changes out to files is supported, in the future support for additional
output destinations can be added.
The StreamingService
is configured from within an App using the AppOptions
loaded from the app.toml file:
[store]
streamers = [ # if len(streamers) > 0 we are streaming
"file", # name of the streaming service, used by constructor
]
[streamers]
[streamers.file]
keys = ["list", "of", "store", "keys", "we", "want", "to", "expose", "for", "this", "streaming", "service"]
write_dir = "path to the write directory"
prefix = "optional prefix to prepend to the generated file names"
store.streamers
contains a list of the names of the StreamingService
implementations to employ which are used by ServiceTypeFromString
to return the ServiceConstructor
for that particular implementation:
listeners := cast.ToStringSlice(appOpts.Get("store.streamers"))
for _, listenerName := range listeners {
constructor, err := ServiceTypeFromString(listenerName)
if err != nil {
// handle error
}
}
streamers
contains a mapping of the specific StreamingService
implementation name to the configuration parameters for that specific service.
streamers.x.keys
contains the list of StoreKey
names for the KVStores to expose using this service and is required by every type of StreamingService
.
In order to expose all KVStores, we can include *
in this list. An empty list is equivalent to turning the service off.
Additional configuration parameters are optional and specific to the implementation.
In the case of the file streaming service, streamers.file.write_dir
contains the path to the
directory to write the files to, and streamers.file.prefix
contains an optional prefix to prepend to the output files to prevent potential collisions
with other App StreamingService
output files.
The ServiceConstructor
accepts AppOptions
, the store keys collected using streamers.x.keys
, a BinaryMarshaller
and
returns a StreamingService
implementation. The AppOptions
are passed in to provide access to any implementation specific configuration options,
e.g. in the case of the file streaming service the streamers.file.write_dir
and streamers.file.prefix
.
streamingService, err := constructor(appOpts, exposeStoreKeys, appCodec)
if err != nil {
// handler error
}
The returned StreamingService
is loaded into the BaseApp using the BaseApp's SetStreamingService
method.
The Stream
method is called on the service to begin the streaming process. Depending on the implementation this process
may be synchronous or asynchronous with the message processing of the state machine.
bApp.SetStreamingService(streamingService)
wg := new(sync.WaitGroup)
quitChan := make(chan struct{})
streamingService.Stream(wg, quitChan)