85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
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package services
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import (
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"context"
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"errors"
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"fmt"
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"sync"
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"github.com/a-h/templ/examples/counter/db"
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"golang.org/x/exp/slog"
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)
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type Counts struct {
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Global int
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Session int
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}
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type IncrementType int
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const (
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IncrementTypeUnknown IncrementType = iota
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IncrementTypeGlobal
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IncrementTypeSession
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)
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var ErrUnknownIncrementType error = errors.New("unknown increment type")
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func NewCount(log *slog.Logger, cs *db.CountStore) Count {
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return Count{
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Log: log,
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CountStore: cs,
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}
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}
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type Count struct {
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Log *slog.Logger
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CountStore *db.CountStore
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}
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func (cs Count) Increment(ctx context.Context, it IncrementType, sessionID string) (counts Counts, err error) {
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// Work out which operations to do.
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var global, session func(ctx context.Context, id string) (count int, err error)
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switch it {
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case IncrementTypeGlobal:
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global = cs.CountStore.Increment
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session = cs.CountStore.Get
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case IncrementTypeSession:
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global = cs.CountStore.Get
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session = cs.CountStore.Increment
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default:
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return counts, ErrUnknownIncrementType
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}
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// Run the operations in parallel.
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var wg sync.WaitGroup
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wg.Add(2)
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errs := make([]error, 2)
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go func() {
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defer wg.Done()
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counts.Global, errs[0] = global(ctx, "global")
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}()
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go func() {
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defer wg.Done()
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counts.Session, errs[1] = session(ctx, sessionID)
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}()
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wg.Wait()
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return counts, errors.Join(errs...)
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}
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func (cs Count) Get(ctx context.Context, sessionID string) (counts Counts, err error) {
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globalAndSessionCounts, err := cs.CountStore.BatchGet(ctx, "global", sessionID)
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if err != nil {
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err = fmt.Errorf("countservice: failed to get counts: %w", err)
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return
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}
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if len(globalAndSessionCounts) != 2 {
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err = fmt.Errorf("countservice: unexpected counts returned, expected 2, got %d", len(globalAndSessionCounts))
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return
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}
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counts.Global = globalAndSessionCounts[0]
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counts.Session = globalAndSessionCounts[1]
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return
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}
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