437dcc875c
* Integrate mt querier with query caching * typo * let the caller set cache status response header * fix TestQueryAPI * make gen-go * handle CachingServiceClient being nil and make gen-go * include namespace in cache key * set signed in user namespace in query_test.go * fix test * remove commented out code * undo services/query/query.go changes * make gen-go * remove namespace requirement * fix tests * fix test * remove namespace from SignedInUser in tests * make gen-go
58 lines
2.6 KiB
Go
58 lines
2.6 KiB
Go
package clientmiddleware
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import (
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"context"
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"github.com/grafana/grafana-plugin-sdk-go/backend"
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"github.com/grafana/grafana/pkg/services/caching"
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"github.com/grafana/grafana/pkg/services/contexthandler"
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)
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// NewCachingMiddleware creates a new backend.HandlerMiddleware that will
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// attempt to read and write query results to the cache
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func NewCachingMiddleware(cachingServiceClient *caching.CachingServiceClient) backend.HandlerMiddleware {
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cachingMiddlewareHandler := func(next backend.Handler) backend.Handler {
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return &CachingMiddleware{
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BaseHandler: backend.NewBaseHandler(next),
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cachingServiceClient: cachingServiceClient,
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}
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}
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return backend.HandlerMiddlewareFunc(cachingMiddlewareHandler)
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}
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// An adapter to use CachingServiceClient as a middleware. If possible prefer to use `CachingServiceClient` directly.
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type CachingMiddleware struct {
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backend.BaseHandler
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cachingServiceClient *caching.CachingServiceClient
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}
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// QueryData receives a data request and attempts to access results already stored in the cache for that request.
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// If data is found, it will return it immediately. Otherwise, it will perform the queries as usual, then write the response to the cache.
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// If the cache service is implemented, we capture the request duration as a metric. The service is expected to write any response headers.
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func (m *CachingMiddleware) QueryData(ctx context.Context, req *backend.QueryDataRequest) (*backend.QueryDataResponse, error) {
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reqCtx := contexthandler.FromContext(ctx)
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if reqCtx == nil {
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return m.BaseHandler.QueryData(ctx, req)
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}
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return m.cachingServiceClient.WithQueryDataCaching(ctx, req, func() (*backend.QueryDataResponse, error) {
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return m.BaseHandler.QueryData(ctx, req)
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})
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}
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// CallResource receives a resource request and attempts to access results already stored in the cache for that request.
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// If data is found, it will return it immediately. Otherwise, it will perform the request as usual. The caller of CallResource is expected to explicitly update the cache with any responses.
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// If the cache service is implemented, we capture the request duration as a metric. The service is expected to write any response headers.
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func (m *CachingMiddleware) CallResource(ctx context.Context, req *backend.CallResourceRequest, sender backend.CallResourceResponseSender) error {
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reqCtx := contexthandler.FromContext(ctx)
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if reqCtx == nil {
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return m.BaseHandler.CallResource(ctx, req, sender)
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}
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return m.cachingServiceClient.WithCallResourceCaching(ctx, req, sender, func(sender backend.CallResourceResponseSender) error {
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return m.BaseHandler.CallResource(ctx, req, sender)
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})
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}
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