hugo/tpl/partials/partials.go
2023-03-01 16:28:43 +01:00

253 lines
6.4 KiB
Go

// Copyright 2017 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package partials provides template functions for working with reusable
// templates.
package partials
import (
"context"
"fmt"
"html/template"
"io"
"strings"
"time"
"github.com/bep/lazycache"
"github.com/gohugoio/hugo/identity"
texttemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate"
"github.com/gohugoio/hugo/tpl"
bp "github.com/gohugoio/hugo/bufferpool"
"github.com/gohugoio/hugo/deps"
)
// TestTemplateProvider is global deps.ResourceProvider.
// NOTE: It's currently unused.
var TestTemplateProvider deps.ResourceProvider
type partialCacheKey struct {
Name string
Variants []any
}
type includeResult struct {
name string
result any
err error
}
func (k partialCacheKey) Key() string {
if k.Variants == nil {
return k.Name
}
return identity.HashString(append([]any{k.Name}, k.Variants...)...)
}
func (k partialCacheKey) templateName() string {
if !strings.HasPrefix(k.Name, "partials/") {
return "partials/" + k.Name
}
return k.Name
}
// partialCache represents a LRU cache of partials.
type partialCache struct {
cache *lazycache.Cache[string, includeResult]
}
func (p *partialCache) clear() {
p.cache.DeleteFunc(func(string, includeResult) bool {
return true
})
}
// New returns a new instance of the templates-namespaced template functions.
func New(deps *deps.Deps) *Namespace {
// This lazycache was introduced in Hugo 0.111.0.
// We're going to expand and consolidate all memory caches in Hugo using this,
// so just set a high limit for now.
lru := lazycache.New[string, includeResult](lazycache.Options{MaxEntries: 1000})
cache := &partialCache{cache: lru}
deps.BuildStartListeners.Add(
func() {
cache.clear()
})
return &Namespace{
deps: deps,
cachedPartials: cache,
}
}
// Namespace provides template functions for the "templates" namespace.
type Namespace struct {
deps *deps.Deps
cachedPartials *partialCache
}
// contextWrapper makes room for a return value in a partial invocation.
type contextWrapper struct {
Arg any
Result any
}
// Set sets the return value and returns an empty string.
func (c *contextWrapper) Set(in any) string {
c.Result = in
return ""
}
// Include executes the named partial.
// If the partial contains a return statement, that value will be returned.
// Else, the rendered output will be returned:
// A string if the partial is a text/template, or template.HTML when html/template.
// Note that ctx is provided by Hugo, not the end user.
func (ns *Namespace) Include(ctx context.Context, name string, contextList ...any) (any, error) {
res := ns.includWithTimeout(ctx, name, contextList...)
if res.err != nil {
return nil, res.err
}
if ns.deps.Metrics != nil {
ns.deps.Metrics.TrackValue(res.name, res.result, false)
}
return res.result, nil
}
func (ns *Namespace) includWithTimeout(ctx context.Context, name string, dataList ...any) includeResult {
ctx, cancel := context.WithTimeout(ctx, ns.deps.Timeout)
defer cancel()
res := make(chan includeResult, 1)
go func() {
res <- ns.include(ctx, name, dataList...)
}()
select {
case r := <-res:
return r
case <-ctx.Done():
err := ctx.Err()
if err == context.DeadlineExceeded {
err = fmt.Errorf("partial %q timed out after %s. This is most likely due to infinite recursion. If this is just a slow template, you can try to increase the 'timeout' config setting.", name, ns.deps.Timeout)
}
return includeResult{err: err}
}
}
// include is a helper function that lookups and executes the named partial.
// Returns the final template name and the rendered output.
func (ns *Namespace) include(ctx context.Context, name string, dataList ...any) includeResult {
var data any
if len(dataList) > 0 {
data = dataList[0]
}
var n string
if strings.HasPrefix(name, "partials/") {
n = name
} else {
n = "partials/" + name
}
templ, found := ns.deps.Tmpl().Lookup(n)
if !found {
// For legacy reasons.
templ, found = ns.deps.Tmpl().Lookup(n + ".html")
}
if !found {
return includeResult{err: fmt.Errorf("partial %q not found", name)}
}
var info tpl.ParseInfo
if ip, ok := templ.(tpl.Info); ok {
info = ip.ParseInfo()
}
var w io.Writer
if info.HasReturn {
// Wrap the context sent to the template to capture the return value.
// Note that the template is rewritten to make sure that the dot (".")
// and the $ variable points to Arg.
data = &contextWrapper{
Arg: data,
}
// We don't care about any template output.
w = io.Discard
} else {
b := bp.GetBuffer()
defer bp.PutBuffer(b)
w = b
}
if err := ns.deps.Tmpl().ExecuteWithContext(ctx, templ, w, data); err != nil {
return includeResult{err: err}
}
var result any
if ctx, ok := data.(*contextWrapper); ok {
result = ctx.Result
} else if _, ok := templ.(*texttemplate.Template); ok {
result = w.(fmt.Stringer).String()
} else {
result = template.HTML(w.(fmt.Stringer).String())
}
return includeResult{
name: templ.Name(),
result: result,
}
}
// IncludeCached executes and caches partial templates. The cache is created with name+variants as the key.
// Note that ctx is provided by Hugo, not the end user.
func (ns *Namespace) IncludeCached(ctx context.Context, name string, context any, variants ...any) (any, error) {
start := time.Now()
key := partialCacheKey{
Name: name,
Variants: variants,
}
r, found, err := ns.cachedPartials.cache.GetOrCreate(key.Key(), func(string) (includeResult, error) {
r := ns.includWithTimeout(ctx, key.Name, context)
return r, r.err
})
if err != nil {
return nil, err
}
if ns.deps.Metrics != nil {
if found {
// The templates that gets executed is measured in Execute.
// We need to track the time spent in the cache to
// get the totals correct.
ns.deps.Metrics.MeasureSince(key.templateName(), start)
}
ns.deps.Metrics.TrackValue(key.templateName(), r.result, found)
}
return r.result, nil
}