API: Rig up File { sha }
This commit is contained in:
Drew DeVault
parent
dd5dbf3240
commit
ec9bcf7fae
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@ -0,0 +1,7 @@
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// This type is not rigged up with GraphQL, and is only used internally.
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package model
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type Blob struct {
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ID int
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SHA string
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}
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@ -19,7 +19,11 @@ import (
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)
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func (r *fileResolver) Sha(ctx context.Context, obj *model.File) (string, error) {
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panic(fmt.Errorf("not implemented"))
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blob, err := loaders.ForContext(ctx).BlobsByID.Load(obj.BlobID)
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if err != nil {
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panic(err)
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}
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return blob.SHA, nil
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}
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func (r *fileResolver) Contents(ctx context.Context, obj *model.File) (*model.URL, error) {
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@ -0,0 +1,224 @@
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// Code generated by github.com/vektah/dataloaden, DO NOT EDIT.
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package loaders
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import (
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"sync"
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"time"
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"git.sr.ht/~sircmpwn/paste.sr.ht/api/graph/model"
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)
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// BlobsByIDLoaderConfig captures the config to create a new BlobsByIDLoader
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type BlobsByIDLoaderConfig struct {
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// Fetch is a method that provides the data for the loader
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Fetch func(keys []int) ([]*model.Blob, []error)
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// Wait is how long wait before sending a batch
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Wait time.Duration
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// MaxBatch will limit the maximum number of keys to send in one batch, 0 = not limit
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MaxBatch int
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}
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// NewBlobsByIDLoader creates a new BlobsByIDLoader given a fetch, wait, and maxBatch
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func NewBlobsByIDLoader(config BlobsByIDLoaderConfig) *BlobsByIDLoader {
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return &BlobsByIDLoader{
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fetch: config.Fetch,
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wait: config.Wait,
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maxBatch: config.MaxBatch,
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}
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}
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// BlobsByIDLoader batches and caches requests
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type BlobsByIDLoader struct {
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// this method provides the data for the loader
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fetch func(keys []int) ([]*model.Blob, []error)
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// how long to done before sending a batch
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wait time.Duration
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// this will limit the maximum number of keys to send in one batch, 0 = no limit
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maxBatch int
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// INTERNAL
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// lazily created cache
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cache map[int]*model.Blob
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// the current batch. keys will continue to be collected until timeout is hit,
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// then everything will be sent to the fetch method and out to the listeners
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batch *blobsByIDLoaderBatch
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// mutex to prevent races
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mu sync.Mutex
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}
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type blobsByIDLoaderBatch struct {
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keys []int
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data []*model.Blob
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error []error
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closing bool
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done chan struct{}
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}
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// Load a Blob by key, batching and caching will be applied automatically
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func (l *BlobsByIDLoader) Load(key int) (*model.Blob, error) {
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return l.LoadThunk(key)()
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}
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// LoadThunk returns a function that when called will block waiting for a Blob.
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// This method should be used if you want one goroutine to make requests to many
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// different data loaders without blocking until the thunk is called.
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func (l *BlobsByIDLoader) LoadThunk(key int) func() (*model.Blob, error) {
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l.mu.Lock()
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if it, ok := l.cache[key]; ok {
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l.mu.Unlock()
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return func() (*model.Blob, error) {
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return it, nil
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}
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}
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if l.batch == nil {
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l.batch = &blobsByIDLoaderBatch{done: make(chan struct{})}
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}
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batch := l.batch
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pos := batch.keyIndex(l, key)
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l.mu.Unlock()
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return func() (*model.Blob, error) {
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<-batch.done
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var data *model.Blob
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if pos < len(batch.data) {
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data = batch.data[pos]
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}
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var err error
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// its convenient to be able to return a single error for everything
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if len(batch.error) == 1 {
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err = batch.error[0]
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} else if batch.error != nil {
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err = batch.error[pos]
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}
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if err == nil {
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l.mu.Lock()
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l.unsafeSet(key, data)
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l.mu.Unlock()
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}
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return data, err
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}
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}
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// LoadAll fetches many keys at once. It will be broken into appropriate sized
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// sub batches depending on how the loader is configured
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func (l *BlobsByIDLoader) LoadAll(keys []int) ([]*model.Blob, []error) {
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results := make([]func() (*model.Blob, error), len(keys))
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for i, key := range keys {
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results[i] = l.LoadThunk(key)
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}
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blobs := make([]*model.Blob, len(keys))
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errors := make([]error, len(keys))
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for i, thunk := range results {
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blobs[i], errors[i] = thunk()
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}
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return blobs, errors
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}
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// LoadAllThunk returns a function that when called will block waiting for a Blobs.
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// This method should be used if you want one goroutine to make requests to many
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// different data loaders without blocking until the thunk is called.
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func (l *BlobsByIDLoader) LoadAllThunk(keys []int) func() ([]*model.Blob, []error) {
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results := make([]func() (*model.Blob, error), len(keys))
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for i, key := range keys {
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results[i] = l.LoadThunk(key)
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}
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return func() ([]*model.Blob, []error) {
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blobs := make([]*model.Blob, len(keys))
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errors := make([]error, len(keys))
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for i, thunk := range results {
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blobs[i], errors[i] = thunk()
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}
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return blobs, errors
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}
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}
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// Prime the cache with the provided key and value. If the key already exists, no change is made
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// and false is returned.
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// (To forcefully prime the cache, clear the key first with loader.clear(key).prime(key, value).)
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func (l *BlobsByIDLoader) Prime(key int, value *model.Blob) bool {
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l.mu.Lock()
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var found bool
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if _, found = l.cache[key]; !found {
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// make a copy when writing to the cache, its easy to pass a pointer in from a loop var
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// and end up with the whole cache pointing to the same value.
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cpy := *value
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l.unsafeSet(key, &cpy)
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}
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l.mu.Unlock()
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return !found
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}
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// Clear the value at key from the cache, if it exists
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func (l *BlobsByIDLoader) Clear(key int) {
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l.mu.Lock()
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delete(l.cache, key)
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l.mu.Unlock()
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}
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func (l *BlobsByIDLoader) unsafeSet(key int, value *model.Blob) {
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if l.cache == nil {
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l.cache = map[int]*model.Blob{}
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}
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l.cache[key] = value
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}
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// keyIndex will return the location of the key in the batch, if its not found
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// it will add the key to the batch
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func (b *blobsByIDLoaderBatch) keyIndex(l *BlobsByIDLoader, key int) int {
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for i, existingKey := range b.keys {
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if key == existingKey {
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return i
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}
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}
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pos := len(b.keys)
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b.keys = append(b.keys, key)
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if pos == 0 {
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go b.startTimer(l)
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}
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if l.maxBatch != 0 && pos >= l.maxBatch-1 {
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if !b.closing {
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b.closing = true
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l.batch = nil
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go b.end(l)
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}
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}
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return pos
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}
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func (b *blobsByIDLoaderBatch) startTimer(l *BlobsByIDLoader) {
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time.Sleep(l.wait)
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l.mu.Lock()
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// we must have hit a batch limit and are already finalizing this batch
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if b.closing {
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l.mu.Unlock()
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return
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}
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l.batch = nil
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l.mu.Unlock()
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b.end(l)
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}
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func (b *blobsByIDLoaderBatch) end(l *BlobsByIDLoader) {
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b.data, b.error = l.fetch(b.keys)
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close(b.done)
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}
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@ -3,6 +3,7 @@ package loaders
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//go:generate ./gen UsersByIDLoader int api/graph/model.User
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//go:generate ./gen UsersByNameLoader string api/graph/model.User
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//go:generate ./gen PastesBySHALoader string api/graph/model.Paste
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//go:generate ./gen BlobsByIDLoader int api/graph/model.Blob
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import (
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"context"
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@ -26,11 +27,50 @@ type contextKey struct {
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}
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type Loaders struct {
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BlobsByID BlobsByIDLoader
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PastesBySHA PastesBySHALoader
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UsersByID UsersByIDLoader
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UsersByName UsersByNameLoader
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}
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func fetchBlobsByID(ctx context.Context) func(ids []int) ([]*model.Blob, []error) {
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return func(ids []int) ([]*model.Blob, []error) {
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blobs := make([]*model.Blob, len(ids))
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if err := database.WithTx(ctx, &sql.TxOptions{
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Isolation: 0,
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ReadOnly: true,
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}, func (tx *sql.Tx) error {
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rows, err := tx.QueryContext(ctx, `
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SELECT id, sha FROM blob WHERE id = ANY($1);
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`, pq.Array(ids))
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if err != nil {
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return err
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}
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defer rows.Close()
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blobsByID := map[int]*model.Blob{}
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for rows.Next() {
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var blob model.Blob
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if err := rows.Scan(&blob.ID, &blob.SHA); err != nil {
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panic(err)
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}
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blobsByID[blob.ID] = &blob
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}
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if err = rows.Err(); err != nil {
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panic(err)
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}
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for i, id := range ids {
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blobs[i] = blobsByID[id]
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}
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return nil
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}); err != nil {
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panic(err)
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}
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return blobs, nil
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}
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}
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func fetchPastesBySHA(ctx context.Context) func(shas []string) ([]*model.Paste, []error) {
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return func(shas []string) ([]*model.Paste, []error) {
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pastes := make([]*model.Paste, len(shas))
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@ -170,6 +210,11 @@ func fetchUsersByName(ctx context.Context) func(names []string) ([]*model.User,
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func Middleware(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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ctx := context.WithValue(r.Context(), loadersCtxKey, &Loaders{
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BlobsByID: BlobsByIDLoader{
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maxBatch: 100,
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wait: 1 * time.Millisecond,
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fetch: fetchBlobsByID(r.Context()),
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},
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PastesBySHA: PastesBySHALoader{
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maxBatch: 100,
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wait: 1 * time.Millisecond,
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