/
filedat.go
191 lines (160 loc) · 3.72 KB
/
filedat.go
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package qdb
import (
"os"
"fmt"
"bytes"
"io/ioutil"
"encoding/binary"
)
// Opens file and checks the ffffffff-sequence-FINI marker at the end
func openAndGetSeq(fn string) (f *os.File, seq uint32) {
var b [12]byte
var e error
var fpos int64
if f, e = os.Open(fn); e != nil {
return
}
if fpos, e = f.Seek(-12, os.SEEK_END); e!=nil || fpos<4 {
println(fn, ":", "openAndGetSeq fseek error", e, fpos)
f.Close()
f = nil
return
}
if _, e = f.Read(b[:]); e != nil {
println(fn, ":", "openAndGetSeq read error", e.Error())
f.Close()
f = nil
return
}
if binary.LittleEndian.Uint32(b[0:4])!=0xffffffff || string(b[8:12])!="FINI" {
println(fn, ":", "openAndGetSeq marker error")
f.Close()
f = nil
return
}
seq = binary.LittleEndian.Uint32(b[4:8])
return
}
func (db *DB) findnewdat() *os.File {
f0, seq0 := openAndGetSeq(db.pathname+"0")
f1, seq1 := openAndGetSeq(db.pathname+"1")
if f0 == nil && f1 == nil {
return nil
}
if f0!=nil && f1!=nil {
// Both files are valid - take the one with higher sequence
if int32(seq0 - seq1) >= 0 {
f1.Close()
os.Remove(db.pathname+"1")
db.version_seq = seq0
db.file_index = 0
return f0
} else {
f0.Close()
f0 = f1
os.Remove(db.pathname+"0")
db.version_seq = seq1
db.file_index = 1
return f1
}
} else if f0==nil {
db.version_seq = seq1
db.file_index = 1
return f1
} else {
db.version_seq = seq0
db.file_index = 0
return f0
}
}
// allocate the cache map and loads it from disk
func (db *DB) loadfiledat() {
var ks uint32
var key KeyType
var pos int64
db.index = make(map[KeyType] *oneIdx)
db.datfile = db.findnewdat()
if db.datfile==nil {
return
}
db.datfile.Seek(0, os.SEEK_SET)
dat, _ := ioutil.ReadAll(db.datfile)
readlimit := int64(len(dat)-12)
for pos+12 <= readlimit {
key = KeyType(binary.LittleEndian.Uint64(dat[pos:pos+8]))
ks = binary.LittleEndian.Uint32(dat[pos+8:pos+12])
if pos+12+int64(ks) > readlimit {
println("loadfiledat EOF")
break
}
if db.NeverKeepInMem {
db.index[key] = &oneIdx{fpos:pos}
} else {
dd := dat[pos+12:pos+12+int64(ks)]
if db.KeepInMem==nil || db.KeepInMem(dd) {
val := make([]byte, ks)
copy(val, dd)
db.index[key] = &oneIdx{data:val, fpos:pos}
} else {
db.index[key] = &oneIdx{fpos:pos}
}
}
pos += int64(KeySize+4+ks)
}
return
}
func (db *DB) savefiledat() {
new_file_index := 1 - db.file_index
fname := fmt.Sprint(db.pathname, new_file_index)
f := new(bytes.Buffer)
var v []byte
var fpos int64
for k, idx := range db.index {
if idx.data == nil {
v = db.loadrec(idx.fpos)
} else {
v = idx.data
}
binary.Write(f, binary.LittleEndian, k)
binary.Write(f, binary.LittleEndian, uint32(len(v)))
f.Write(v)
idx.fpos = fpos
/*if !db.NeverKeepInMem && (db.KeepInMem==nil || db.KeepInMem(v)) {
idx.data = v
}*/
fpos += KeySize+4+int64(len(v))
}
f.Write([]byte{0xff,0xff,0xff,0xff})
binary.Write(f, binary.LittleEndian, uint32(db.version_seq+1))
f.Write([]byte("FINI"))
fi, _ := os.Create(fname)
fi.Write(f.Bytes())
fi.Sync()
if db.datfile!=nil {
db.datfile.Close()
os.Remove(fmt.Sprint(db.pathname, db.file_index))
}
db.datfile = fi
if db.logfile!=nil {
db.logfile.Close()
os.Remove(db.pathname+"log")
db.logfile = nil
}
db.version_seq++
db.file_index = new_file_index
}
func (db *DB) loadrec(fpos int64) (value []byte) {
var u32 uint32
if fpos< 0 {
db.logfile.Seek(int64(-fpos)+KeySize+1, os.SEEK_SET)
binary.Read(db.logfile, binary.LittleEndian, &u32)
value = make([]byte, u32)
db.logfile.Read(value)
} else {
db.datfile.Seek(int64(fpos)+KeySize, os.SEEK_SET)
binary.Read(db.datfile, binary.LittleEndian, &u32)
value = make([]byte, u32)
db.datfile.Read(value)
}
return
}