Files
weave-scope/extras/generate_latest_map
2020-12-30 18:30:34 +00:00

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#!/usr/bin/env bash
#
# Generate concrete implementations of LatestMap.
#
# e.g.
# $ generate_latest_map ./report/out.go string NodeControlData ...
#
# Depends on:
# - gofmt
function generate_header() {
local out_file="${1}"
local cmd="${2}"
cat <<EOF >"${out_file}"
// Generated file, do not edit.
// To regenerate, run ${cmd}
package report
import (
"bytes"
"fmt"
"sort"
"time"
"github.com/ugorji/go/codec"
)
EOF
}
function generate_latest_map() {
local out_file="$1"
local data_type="$2"
local uppercase_data_type="${data_type^}"
local lowercase_data_type="${data_type,}"
local entry_type="${lowercase_data_type}LatestEntry"
local latest_map_type="${uppercase_data_type}LatestMap"
local make_function="Make${latest_map_type}"
# shellcheck disable=SC2016
local json_timestamp='`json:"timestamp"`'
# shellcheck disable=SC2016
local json_value='`json:"value"`'
cat <<EOF >>"${out_file}"
type ${entry_type} struct {
key string
Timestamp time.Time ${json_timestamp}
Value ${data_type} ${json_value}
dummySelfer
}
// String returns the StringLatestEntry's string representation.
func (e *${entry_type}) String() string {
return fmt.Sprintf("%v (%s)", e.Value, e.Timestamp.Format(time.RFC3339))
}
// Equal returns true if the supplied StringLatestEntry is equal to this one.
func (e *${entry_type}) Equal(e2 *${entry_type}) bool {
return e.Timestamp.Equal(e2.Timestamp) && e.Value == e2.Value
}
// ${latest_map_type} holds latest ${data_type} instances, as a slice sorted by key.
type ${latest_map_type} []${entry_type}
// ${make_function} makes an empty ${latest_map_type}.
func ${make_function}() ${latest_map_type} {
return ${latest_map_type}{}
}
// Size returns the number of elements.
func (m ${latest_map_type}) Size() int {
return len(m)
}
// Merge produces a ${latest_map_type} containing the keys from both inputs.
// When both inputs contain the same key, the newer value is used.
// Tries to return one of its inputs, if that already holds the correct result.
func (m ${latest_map_type}) Merge(n ${latest_map_type}) ${latest_map_type} {
switch {
case len(m) == 0:
return n
case len(n) == 0:
return m
}
if len(n) > len(m) {
m, n = n, m //swap so m is always at least as long as n
} else if len(n) == len(m) && m[0].Timestamp.Before(n[0].Timestamp) {
// Optimise common case where we merge two nodes with the same contents
// sampled at different times.
m, n = n, m // swap equal-length arrays so first element of m is newer
}
i, j := 0, 0
loop:
for i < len(m) {
switch {
case j >= len(n):
return m
case m[i].key == n[j].key:
if m[i].Timestamp.Before(n[j].Timestamp) {
break loop
}
i++
j++
case m[i].key < n[j].key:
i++
default:
break loop
}
}
if i >= len(m) && j >= len(n) {
return m
}
out := make([]${entry_type}, i, len(m))
copy(out, m[:i])
for i < len(m) {
switch {
case j >= len(n):
out = append(out, m[i:]...)
return out
case m[i].key == n[j].key:
if m[i].Timestamp.Before(n[j].Timestamp) {
out = append(out, n[j])
} else {
out = append(out, m[i])
}
i++
j++
case m[i].key < n[j].key:
out = append(out, m[i])
i++
default:
out = append(out, n[j])
j++
}
}
out = append(out, n[j:]...)
return out
}
// Lookup the value for the given key.
func (m ${latest_map_type}) Lookup(key string) (${data_type}, bool) {
v, _, ok := m.LookupEntry(key)
if !ok {
var zero ${data_type}
return zero, false
}
return v, true
}
// LookupEntry returns the raw entry for the given key.
func (m ${latest_map_type}) LookupEntry(key string) (${data_type}, time.Time, bool) {
i := sort.Search(len(m), func(i int) bool {
return m[i].key >= key
})
if i < len(m) && m[i].key == key {
return m[i].Value, m[i].Timestamp, true
}
var zero ${data_type}
return zero, time.Time{}, false
}
// locate the position where key should go, and make room for it if not there already
func (m *${latest_map_type}) locate(key string) int {
i := sort.Search(len(*m), func(i int) bool {
return (*m)[i].key >= key
})
// i is now the position where key should go, either at the end or in the middle
if i == len(*m) || (*m)[i].key != key {
*m = append(*m, ${entry_type}{})
copy((*m)[i+1:], (*m)[i:])
(*m)[i] = ${entry_type}{}
}
return i
}
// Set the value for the given key.
func (m ${latest_map_type}) Set(key string, timestamp time.Time, value ${data_type}) ${latest_map_type} {
i := sort.Search(len(m), func(i int) bool {
return m[i].key >= key
})
// i is now the position where key should go, either at the end or in the middle
oldEntries := m
if i == len(m) {
m = make([]${entry_type}, len(oldEntries)+1)
copy(m, oldEntries)
} else if m[i].key == key {
m = make([]${entry_type}, len(oldEntries))
copy(m, oldEntries)
} else {
m = make([]${entry_type}, len(oldEntries)+1)
copy(m, oldEntries[:i])
copy(m[i+1:], oldEntries[i:])
}
m[i] = ${entry_type}{key: key, Timestamp: timestamp, Value: value}
return m
}
// ForEach executes fn on each key value pair in the map.
func (m ${latest_map_type}) ForEach(fn func(k string, timestamp time.Time, v ${data_type})) {
for _, value := range m {
fn(value.key, value.Timestamp, value.Value)
}
}
// String returns the ${latest_map_type}'s string representation.
func (m ${latest_map_type}) String() string {
buf := bytes.NewBufferString("{")
for _, val := range m {
fmt.Fprintf(buf, "%s: %s,\\n", val.key, val.String())
}
fmt.Fprintf(buf, "}")
return buf.String()
}
// DeepEqual tests equality with other ${latest_map_type}.
func (m ${latest_map_type}) DeepEqual(n ${latest_map_type}) bool {
if m.Size() != n.Size() {
return false
}
for i := range m {
if m[i].key != n[i].key || !m[i].Equal(&n[i]) {
return false
}
}
return true
}
// EqualIgnoringTimestamps returns true if all keys and values are the same.
func (m ${latest_map_type}) EqualIgnoringTimestamps(n ${latest_map_type}) bool {
if m.Size() != n.Size() {
return false
}
for i := range m {
if m[i].key != n[i].key || m[i].Value != n[i].Value {
return false
}
}
return true
}
// CodecEncodeSelf implements codec.Selfer.
// Duplicates the output for a built-in map without generating an
// intermediate copy of the data structure, to save time. Note this
// means we are using undocumented, internal APIs, which could break
// in the future. See https://github.com/weaveworks/scope/pull/1709
// for more information.
func (m ${latest_map_type}) CodecEncodeSelf(encoder *codec.Encoder) {
z, r := codec.GenHelperEncoder(encoder)
if m == nil {
r.EncodeNil()
return
}
r.EncodeMapStart(m.Size())
for _, val := range m {
z.EncSendContainerState(containerMapKey)
r.EncodeString(cUTF8, val.key)
z.EncSendContainerState(containerMapValue)
val.CodecEncodeSelf(encoder)
}
z.EncSendContainerState(containerMapEnd)
}
// CodecDecodeSelf implements codec.Selfer.
// Decodes the input as for a built-in map, without creating an
// intermediate copy of the data structure to save time. Uses
// undocumented, internal APIs as for CodecEncodeSelf.
func (m *${latest_map_type}) CodecDecodeSelf(decoder *codec.Decoder) {
*m = nil
z, r := codec.GenHelperDecoder(decoder)
if r.TryDecodeAsNil() {
return
}
length := r.ReadMapStart()
if length > 0 {
*m = make([]${entry_type}, 0, length)
}
for i := 0; length < 0 || i < length; i++ {
if length < 0 && r.CheckBreak() {
break
}
z.DecSendContainerState(containerMapKey)
var key string
if !r.TryDecodeAsNil() {
key = lookupCommonKey(r.DecodeStringAsBytes())
}
i := m.locate(key)
(*m)[i].key = key
z.DecSendContainerState(containerMapValue)
if !r.TryDecodeAsNil() {
(*m)[i].CodecDecodeSelf(decoder)
}
}
z.DecSendContainerState(containerMapEnd)
}
// MarshalJSON shouldn't be used, use CodecEncodeSelf instead.
func (${latest_map_type}) MarshalJSON() ([]byte, error) {
panic("MarshalJSON shouldn't be used, use CodecEncodeSelf instead")
}
// UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead.
func (*${latest_map_type}) UnmarshalJSON(b []byte) error {
panic("UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead")
}
EOF
}
if [ -z "${1}" ]; then
echo "No output file given"
exit 1
fi
out="${1}"
outtmp="${out}.tmp"
generate_header "${outtmp}" "${0} ${*}"
shift
for t in "${@}"; do
generate_latest_map "${outtmp}" "${t}"
done
gofmt -s -w "${outtmp}"
mv "${outtmp}" "${out}"