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Remove inappropriate use of context in ingestion endpoints
Commit 9161997 used a request context to ensure that all queries to the horizon database from ingestion endpoints were wrapped in a repeatable read transaction. This commit refactors the ingestion endpoints to acheive the same effect without using a context to store a request scoped database session.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,122 @@ | ||
| package actions | ||
|
|
||
| import ( | ||
| "database/sql" | ||
| "net/http" | ||
| "strconv" | ||
|
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| "github.com/stellar/go/services/horizon/internal/db2/history" | ||
| "github.com/stellar/go/support/errors" | ||
| "github.com/stellar/go/support/render/hal" | ||
| ) | ||
|
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| // LastLedgerHeaderName is the header which is set on all experimental ingestion endpoints | ||
| const LastLedgerHeaderName = "Latest-Ledger" | ||
|
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| // HeaderWriter is an interface for setting HTTP response headers | ||
| type HeaderWriter interface { | ||
| Header() http.Header | ||
| } | ||
|
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| // StreamableObjectResponse is an interface for objects returned by streamable object endpoints | ||
| // A streamable object endpoint is an SSE endpoint which returns a single JSON object response | ||
| // instead of a page of items. | ||
| type StreamableObjectResponse interface { | ||
| Equals(other StreamableObjectResponse) bool | ||
| } | ||
|
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| // PageHandler represents a handler for a horizon endpoint which produces a response body | ||
| // consisting of a list of `hal.Pageable` items | ||
| type PageHandler interface { | ||
| GetResourcePage(w HeaderWriter, r *http.Request) ([]hal.Pageable, error) | ||
| } | ||
|
|
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| // StreamableObjectHandler represents a handler for a horizon endpoint which produces a | ||
| // response body consisting of a single `StreamableObjectResponse` instance | ||
| type StreamableObjectHandler interface { | ||
| GetResource( | ||
| w HeaderWriter, | ||
| r *http.Request, | ||
| ) (StreamableObjectResponse, error) | ||
| } | ||
|
|
||
| // ObjectHandler represents a handler for a horizon endpoint which produces a | ||
| // response body consisting of a single `hal.Pageable` instance | ||
| type ObjectHandler interface { | ||
| GetResource( | ||
| w HeaderWriter, | ||
| r *http.Request, | ||
| ) (hal.Pageable, error) | ||
| } | ||
|
|
||
| func repeatableReadSession(source *history.Q, r *http.Request) (*history.Q, error) { | ||
| repeatableReadSession := source.Clone() | ||
| repeatableReadSession.Ctx = r.Context() | ||
| err := repeatableReadSession.BeginTx(&sql.TxOptions{ | ||
| Isolation: sql.LevelRepeatableRead, | ||
| ReadOnly: true, | ||
| }) | ||
| if err != nil { | ||
| return nil, errors.Wrap(err, "could not begin repeatable read transaction") | ||
| } | ||
| return &history.Q{repeatableReadSession}, nil | ||
| } | ||
|
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| // SetLastLedgerHeader sets the Latest-Ledger header | ||
| func SetLastLedgerHeader(w HeaderWriter, lastIngestedLedger uint32) { | ||
| w.Header().Set(LastLedgerHeaderName, strconv.FormatUint(uint64(lastIngestedLedger), 10)) | ||
| } | ||
|
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| func fetchAndSetLastLedgerHeader(w HeaderWriter, historyQ *history.Q) error { | ||
| lastIngestedLedger, err := historyQ.GetLastLedgerExpIngestNonBlocking() | ||
| if err != nil { | ||
| return errors.Wrap(err, "could not determine last ingested ledger") | ||
| } | ||
|
|
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| SetLastLedgerHeader(w, lastIngestedLedger) | ||
| return nil | ||
| } | ||
|
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| type repeatableReadPageHandler struct { | ||
| historyQ *history.Q | ||
| withQ func(*history.Q) PageHandler | ||
| } | ||
|
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| func (handler repeatableReadPageHandler) GetResourcePage( | ||
| w HeaderWriter, | ||
| r *http.Request, | ||
| ) ([]hal.Pageable, error) { | ||
| historyQ, err := repeatableReadSession(handler.historyQ, r) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer historyQ.Rollback() | ||
|
|
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| if err = fetchAndSetLastLedgerHeader(w, historyQ); err != nil { | ||
| return nil, err | ||
| } | ||
|
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| return handler.withQ(historyQ).GetResourcePage(w, r) | ||
| } | ||
|
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| type repeatableReadObjectHandler struct { | ||
| historyQ *history.Q | ||
| withQ func(*history.Q) ObjectHandler | ||
| } | ||
|
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| func (handler repeatableReadObjectHandler) GetResource( | ||
| w HeaderWriter, | ||
| r *http.Request, | ||
| ) (hal.Pageable, error) { | ||
| historyQ, err := repeatableReadSession(handler.historyQ, r) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer historyQ.Rollback() | ||
|
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| if err = fetchAndSetLastLedgerHeader(w, historyQ); err != nil { | ||
| return nil, err | ||
| } | ||
|
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| return handler.withQ(historyQ).GetResource(w, r) | ||
| } |
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