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services/horizon/internal/actions: Wrap SSE handlers in repeatable read tx #2344

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merged 3 commits into from
Mar 6, 2020
Merged

services/horizon/internal/actions: Wrap SSE handlers in repeatable read tx #2344

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105ef84
Fetch account from core db in repeatable read tx
tamirms Feb 28, 2020
eb9350f
Execute SSE handler in repeatable read transaction
tamirms Feb 28, 2020
b2752bc
Merge branch 'master' into fix-account-comparison
tamirms Mar 6, 2020
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12 changes: 11 additions & 1 deletion services/horizon/internal/actions/account.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package actions

import (
"context"
"database/sql"
"net/http"
"strings"

Expand All @@ -25,7 +26,16 @@ func accountFromCoreDB(ctx context.Context, cq *core.Q, addr string) (*protocol.
resource protocol.Account
)

err := cq.AccountByAddress(&coreRecord, addr)
err := cq.BeginTx(&sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
})
if err != nil {
return nil, errors.Wrap(err, "starting repeatable read transaction")
}
defer cq.Rollback()

err = cq.AccountByAddress(&coreRecord, addr)
if err != nil {
return nil, errors.Wrap(err, "getting core account record")
}
Expand Down
36 changes: 32 additions & 4 deletions services/horizon/internal/handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,14 @@ import (
"bytes"
"context"
"crypto/sha256"
"database/sql"
"encoding/json"
"net/http"
"strings"
"time"

"github.com/stellar/go/services/horizon/internal/actions"
horizonContext "github.com/stellar/go/services/horizon/internal/context"
"github.com/stellar/go/services/horizon/internal/db2"
"github.com/stellar/go/services/horizon/internal/hchi"
"github.com/stellar/go/services/horizon/internal/ledger"
Expand All @@ -18,6 +20,7 @@ import (
"github.com/stellar/go/services/horizon/internal/render/sse"
"github.com/stellar/go/services/horizon/internal/toid"
"github.com/stellar/go/strkey"
"github.com/stellar/go/support/db"
"github.com/stellar/go/support/errors"
"github.com/stellar/go/support/render/hal"
"github.com/stellar/go/support/render/httpjson"
Expand Down Expand Up @@ -413,6 +416,31 @@ func (handler streamableObjectActionHandler) ServeHTTP(
problem.Render(r.Context(), w, hProblem.NotAcceptable)
}

func repeatableReadStream(
r *http.Request,
generateEvents sse.GenerateEventsFunc,
) sse.GenerateEventsFunc {
var session db.SessionInterface
if val := r.Context().Value(&horizonContext.SessionContextKey); val != nil {
session = val.(db.SessionInterface)
}

return func() ([]sse.Event, error) {
if session != nil {
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@tamirms under which scenarios would session be nil?

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all horizon handlers should have a non nil session. This check is only included because some of the handlers in services/horizon/internal/stream_handler_test.go do not include a session in the request context

err := session.BeginTx(&sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
})
if err != nil {
return nil, errors.Wrap(err, "Error starting repeatable read transaction")
}
defer session.Rollback()
}

return generateEvents()
}
}

func (handler streamableObjectActionHandler) renderStream(
w http.ResponseWriter,
r *http.Request,
Expand All @@ -423,7 +451,7 @@ func (handler streamableObjectActionHandler) renderStream(
w,
r,
singleObjectStreamLimit,
func() ([]sse.Event, error) {
repeatableReadStream(r, func() ([]sse.Event, error) {
response, err := handler.action.GetResource(w, r)
if err != nil {
return nil, err
Expand All @@ -434,7 +462,7 @@ func (handler streamableObjectActionHandler) renderStream(
return []sse.Event{sse.Event{Data: response}}, nil
}
return []sse.Event{}, nil
},
}),
)
}

Expand Down Expand Up @@ -495,7 +523,7 @@ func (handler pageActionHandler) renderStream(w http.ResponseWriter, r *http.Req
w,
r,
int(pq.Limit),
func() ([]sse.Event, error) {
repeatableReadStream(r, func() ([]sse.Event, error) {
records, err := handler.action.GetResourcePage(w, r)
if err != nil {
return nil, err
Expand All @@ -515,7 +543,7 @@ func (handler pageActionHandler) renderStream(w http.ResponseWriter, r *http.Req
}

return events, nil
},
}),
)
}

Expand Down
79 changes: 79 additions & 0 deletions services/horizon/internal/stream_handler_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package horizon

import (
"context"
"database/sql"
"encoding/json"
"fmt"
"net/http"
Expand All @@ -14,8 +15,10 @@ import (

"github.com/go-chi/chi"
"github.com/stellar/go/services/horizon/internal/actions"
horizonContext "github.com/stellar/go/services/horizon/internal/context"
"github.com/stellar/go/services/horizon/internal/ledger"
"github.com/stellar/go/services/horizon/internal/render/sse"
"github.com/stellar/go/support/db"
"github.com/stellar/go/support/render/hal"
)

Expand Down Expand Up @@ -462,3 +465,79 @@ func TestObjectStream(t *testing.T) {
st.Wait(true)
})
}

func TestRepeatableReadStream(t *testing.T) {
t.Run("page stream creates repeatable read tx", func(t *testing.T) {
action := &testPageAction{
objects: map[uint32][]string{
3: []string{"a", "b", "c"},
4: []string{"a", "b", "c", "d", "e"},
},
}

session := &db.MockSession{}
session.On("BeginTx", &sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
}).Return(nil).Once()
session.On("Rollback").Return(nil).Once()

session.On("BeginTx", &sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
}).Return(nil).Once()
session.On("Rollback").Return(nil).Once()

request := streamRequest(t, "")
request = request.WithContext(context.WithValue(
request.Context(),
&horizonContext.SessionContextKey,
session,
))

st := NewStreamablePageTest(
action,
3,
request,
expectResponse(t, unmarashalPage, []string{"a", "b", "c", "d", "e"}),
)
st.Wait(false)
})

t.Run("object stream creates repeatable read tx", func(t *testing.T) {
action := &testObjectAction{
objects: map[uint32]stringObject{
3: "a",
4: "b",
},
}

session := &db.MockSession{}
session.On("BeginTx", &sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
}).Return(nil).Once()
session.On("Rollback").Return(nil).Once()

session.On("BeginTx", &sql.TxOptions{
Isolation: sql.LevelRepeatableRead,
ReadOnly: true,
}).Return(nil).Once()
session.On("Rollback").Return(nil).Once()

request := streamRequest(t, "")
request = request.WithContext(context.WithValue(
request.Context(),
&horizonContext.SessionContextKey,
session,
))

st := NewstreamableObjectTest(
action,
3,
request,
expectResponse(t, unmarashalString, []string{"a", "b"}),
)
st.Wait(false)
})
}
1 change: 1 addition & 0 deletions support/db/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,7 @@ type Session struct {
}

type SessionInterface interface {
BeginTx(opts *sql.TxOptions) error
Begin() error
Rollback() error
TruncateTables(tables []string) error
Expand Down
5 changes: 5 additions & 0 deletions support/db/mock_session.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,11 @@ func (m *MockSession) Begin() error {
return args.Error(0)
}

func (m *MockSession) BeginTx(opts *sql.TxOptions) error {
args := m.Called(opts)
return args.Error(0)
}

func (m *MockSession) Rollback() error {
args := m.Called()
return args.Error(0)
Expand Down