[feature] simpler cache size configuration (#2051)

* add automatic cache max size generation based on ratios of a singular fixed memory target

Signed-off-by: kim <grufwub@gmail.com>

* remove now-unused cache max-size config variables

Signed-off-by: kim <grufwub@gmail.com>

* slight ratio tweak

Signed-off-by: kim <grufwub@gmail.com>

* remove unused visibility config var

Signed-off-by: kim <grufwub@gmail.com>

* add secret little ratio config trick

Signed-off-by: kim <grufwub@gmail.com>

* fixed a word

Signed-off-by: kim <grufwub@gmail.com>

* update cache library to remove use of TTL in result caches + slice cache

Signed-off-by: kim <grufwub@gmail.com>

* update other cache usages to use correct interface

Signed-off-by: kim <grufwub@gmail.com>

* update example config to explain the cache memory target

Signed-off-by: kim <grufwub@gmail.com>

* update env parsing test with new config values

Signed-off-by: kim <grufwub@gmail.com>

* do some ratio twiddling

Signed-off-by: kim <grufwub@gmail.com>

* add missing header

* update envparsing with latest defaults

Signed-off-by: kim <grufwub@gmail.com>

* update size calculations to take into account result cache, simple cache and extra map overheads

Signed-off-by: kim <grufwub@gmail.com>

* tweak the ratios some more

Signed-off-by: kim <grufwub@gmail.com>

* more nan rampaging

Signed-off-by: kim <grufwub@gmail.com>

* fix envparsing script

Signed-off-by: kim <grufwub@gmail.com>

* update cache library, add sweep function to keep caches trim

Signed-off-by: kim <grufwub@gmail.com>

* sweep caches once a minute

Signed-off-by: kim <grufwub@gmail.com>

* add a regular job to sweep caches and keep under 80% utilisation

Signed-off-by: kim <grufwub@gmail.com>

* remove dead code

Signed-off-by: kim <grufwub@gmail.com>

* add new size library used to libraries section of readme

Signed-off-by: kim <grufwub@gmail.com>

* add better explanations for the mem-ratio numbers

Signed-off-by: kim <grufwub@gmail.com>

* update go-cache

Signed-off-by: kim <grufwub@gmail.com>

* library version bump

Signed-off-by: kim <grufwub@gmail.com>

* update cache.result{} size model estimation

Signed-off-by: kim <grufwub@gmail.com>

---------

Signed-off-by: kim <grufwub@gmail.com>

internal/cache/visibility.go

@@ -20,6 +20,7 @@ package cache
 import (
 	"codeberg.org/gruf/go-cache/v3/result"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
 type VisibilityCache struct {
@@ -29,6 +30,14 @@ type VisibilityCache struct {
 // Init will initialize the visibility cache in this collection.
 // NOTE: the cache MUST NOT be in use anywhere, this is not thread-safe.
 func (c *VisibilityCache) Init() {
+	// Calculate maximum cache size.
+	cap := calculateResultCacheMax(
+		sizeofVisibility(), // model in-mem size.
+		config.GetCacheVisibilityMemRatio(),
+	)
+
+	log.Infof(nil, "Visibility cache size = %d", cap)
+
 	c.Cache = result.New([]result.Lookup{
 		{Name: "ItemID", Multi: true},
 		{Name: "RequesterID", Multi: true},
@@ -37,19 +46,17 @@ func (c *VisibilityCache) Init() {
 		v2 := new(CachedVisibility)
 		*v2 = *v1
 		return v2
-	}, config.GetCacheVisibilityMaxSize())
-	c.Cache.SetTTL(config.GetCacheVisibilityTTL(), true)
+	}, cap)
+
 	c.Cache.IgnoreErrors(ignoreErrors)
 }
 
 // Start will attempt to start the visibility cache, or panic.
 func (c *VisibilityCache) Start() {
-	tryStart(c.Cache, config.GetCacheVisibilitySweepFreq())
 }
 
 // Stop will attempt to stop the visibility cache, or panic.
 func (c *VisibilityCache) Stop() {
-	tryStop(c.Cache, config.GetCacheVisibilitySweepFreq())
 }
 
 // VisibilityType represents a visibility lookup type.