frostfs-node/pkg/util/locode/table/csv/table.go
Leonard Lyubich 977229eb5a [] locode/csv: Scan subdivision csv-table into memory
Scanning subdivision csv-table entries one-by-one takes significant time and
system resources. To speed up random access to table records, on the first
call, the table is pumped into memory (map). On subsequent calls, I/O
operations are not performed.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2021-02-10 21:11:28 +03:00

75 lines
1.6 KiB
Go

package csvlocode
import (
"fmt"
"os"
"sync"
)
// Prm groups the required parameters of the Table's constructor.
//
// All values must comply with the requirements imposed on them.
// Passing incorrect parameter values will result in constructor
// failure (error or panic depending on the implementation).
type Prm struct {
// Path to UN/LOCODE csv table.
//
// Must not be empty.
Path string
// Path to csv table of UN/LOCODE Subdivisions.
//
// Must not be empty.
SubDivPath string
}
// Table is a descriptor of the UN/LOCODE table in csv format.
//
// For correct operation, Table must be created
// using the constructor (New) based on the required parameters
// and optional components. After successful creation,
// The Table is immediately ready to work through API.
type Table struct {
paths []string
mode os.FileMode
subDivPath string
subDivOnce sync.Once
mSubDiv map[subDivKey]subDivRecord
}
const invalidPrmValFmt = "invalid parameter %s (%T):%v"
func panicOnPrmValue(n string, v interface{}) {
panic(fmt.Sprintf(invalidPrmValFmt, n, v, v))
}
// New creates a new instance of the Table.
//
// Panics if at least one value of the parameters is invalid.
//
// The created Table does not require additional
// initialization and is completely ready for work.
func New(prm Prm, opts ...Option) *Table {
switch {
case prm.Path == "":
panicOnPrmValue("Path", prm.Path)
case prm.SubDivPath == "":
panicOnPrmValue("SubDivPath", prm.SubDivPath)
}
o := defaultOpts()
for i := range opts {
opts[i](o)
}
return &Table{
paths: append(o.extraPaths, prm.Path),
mode: o.mode,
subDivPath: prm.SubDivPath,
}
}