[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>

vendor/github.com/DmitriyVTitov/size/.gitignore

@@ -0,0 +1,19 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+example
+.idea
+go.sum

vendor/github.com/DmitriyVTitov/size/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Dmitriy Titov (Дмитрий Титов)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/DmitriyVTitov/size/README.md

@@ -0,0 +1,48 @@
+# size - calculates variable's memory consumption at runtime
+
+### Part of the [Transflow Project](http://transflow.ru/)
+
+Sometimes you may need a tool to measure the size of object in your Go program at runtime. This package makes an attempt to do so. Package based on `binary.Size()` from Go standard library.
+
+Features:
+- supports non-fixed size variables and struct fields: `struct`, `int`, `slice`, `string`, `map`;
+- supports complex types including structs with non-fixed size fields;
+- supports all basic types (numbers, bool);
+- supports `chan` and `interface`;
+- supports pointers;
+- implements infinite recursion detection (i.e. pointer inside struct field references to parent struct).
+
+### Usage example
+
+```
+package main
+
+import (
+	"fmt"
+
+	// Use latest tag.
+	"github.com/DmitriyVTitov/size"
+)
+
+func main() {
+	a := struct {
+		a int
+		b string
+		c bool
+		d int32
+		e []byte
+		f [3]int64
+	}{
+		a: 10,                    // 8 bytes
+		b: "Text",                // 16 (string itself) + 4 = 20 bytes
+		c: true,                  // 1 byte
+		d: 25,                    // 4 bytes
+		e: []byte{'c', 'd', 'e'}, // 24 (slice itself) + 3 = 27 bytes
+		f: [3]int64{1, 2, 3},     // 3 * 8 = 24 bytes
+	} // 84 + 3 (padding) = 87 bytes
+
+	fmt.Println(size.Of(a))
+}
+
+// Output: 87
+```

vendor/github.com/DmitriyVTitov/size/size.go

@@ -0,0 +1,142 @@
+// Package size implements run-time calculation of size of the variable.
+// Source code is based on "binary.Size()" function from Go standard library.
+// size.Of() omits size of slices, arrays and maps containers itself (24, 24 and 8 bytes).
+// When counting maps separate calculations are done for keys and values.
+package size
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// Of returns the size of 'v' in bytes.
+// If there is an error during calculation, Of returns -1.
+func Of(v interface{}) int {
+	// Cache with every visited pointer so we don't count two pointers
+	// to the same memory twice.
+	cache := make(map[uintptr]bool)
+	return sizeOf(reflect.Indirect(reflect.ValueOf(v)), cache)
+}
+
+// sizeOf returns the number of bytes the actual data represented by v occupies in memory.
+// If there is an error, sizeOf returns -1.
+func sizeOf(v reflect.Value, cache map[uintptr]bool) int {
+	switch v.Kind() {
+
+	case reflect.Array:
+		sum := 0
+		for i := 0; i < v.Len(); i++ {
+			s := sizeOf(v.Index(i), cache)
+			if s < 0 {
+				return -1
+			}
+			sum += s
+		}
+
+		return sum + (v.Cap()-v.Len())*int(v.Type().Elem().Size())
+
+	case reflect.Slice:
+		// return 0 if this node has been visited already
+		if cache[v.Pointer()] {
+			return 0
+		}
+		cache[v.Pointer()] = true
+
+		sum := 0
+		for i := 0; i < v.Len(); i++ {
+			s := sizeOf(v.Index(i), cache)
+			if s < 0 {
+				return -1
+			}
+			sum += s
+		}
+
+		sum += (v.Cap() - v.Len()) * int(v.Type().Elem().Size())
+
+		return sum + int(v.Type().Size())
+
+	case reflect.Struct:
+		sum := 0
+		for i, n := 0, v.NumField(); i < n; i++ {
+			s := sizeOf(v.Field(i), cache)
+			if s < 0 {
+				return -1
+			}
+			sum += s
+		}
+
+		// Look for struct padding.
+		padding := int(v.Type().Size())
+		for i, n := 0, v.NumField(); i < n; i++ {
+			padding -= int(v.Field(i).Type().Size())
+		}
+
+		return sum + padding
+
+	case reflect.String:
+		s := v.String()
+		hdr := (*reflect.StringHeader)(unsafe.Pointer(&s))
+		if cache[hdr.Data] {
+			return int(v.Type().Size())
+		}
+		cache[hdr.Data] = true
+		return len(s) + int(v.Type().Size())
+
+	case reflect.Ptr:
+		// return Ptr size if this node has been visited already (infinite recursion)
+		if cache[v.Pointer()] {
+			return int(v.Type().Size())
+		}
+		cache[v.Pointer()] = true
+		if v.IsNil() {
+			return int(reflect.New(v.Type()).Type().Size())
+		}
+		s := sizeOf(reflect.Indirect(v), cache)
+		if s < 0 {
+			return -1
+		}
+		return s + int(v.Type().Size())
+
+	case reflect.Bool,
+		reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+		reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Int, reflect.Uint,
+		reflect.Chan,
+		reflect.Uintptr,
+		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128,
+		reflect.Func:
+		return int(v.Type().Size())
+
+	case reflect.Map:
+		// return 0 if this node has been visited already (infinite recursion)
+		if cache[v.Pointer()] {
+			return 0
+		}
+		cache[v.Pointer()] = true
+		sum := 0
+		keys := v.MapKeys()
+		for i := range keys {
+			val := v.MapIndex(keys[i])
+			// calculate size of key and value separately
+			sv := sizeOf(val, cache)
+			if sv < 0 {
+				return -1
+			}
+			sum += sv
+			sk := sizeOf(keys[i], cache)
+			if sk < 0 {
+				return -1
+			}
+			sum += sk
+		}
+		// Include overhead due to unused map buckets.  10.79 comes
+		// from https://golang.org/src/runtime/map.go.
+		return sum + int(v.Type().Size()) + int(float64(len(keys))*10.79)
+
+	case reflect.Interface:
+		return sizeOf(v.Elem(), cache) + int(v.Type().Size())
+
+	}
+
+	return -1
+}