vycb / gdbmc.nim

a wrapper to C GDBM library

This library is a wrapper to C GDBM one

The GNU dbm ('gdbm') is a library of database functions that use extendable hashing and works similarly to the standard UNIX 'dbm' functions.

Instal:

nimble install gdbmc  

Requirement:

By default **libgdbm.so.*** already installed on most distros.  
sudo apt install libgdbm  

Usage:

    block test:
      const filename: string = "test.db"
      let
        db = Open(filename, "n")
      defer: Close(db)

      ## Inserts a key-value pair in the database
      let seqdata = @[("test2", "test2value"), ("test3", "test3value"), ("test4", "test4value"), ("test5", "test5value")]

      for seqitem in seqdata:
        (serr,errl) = Insert(db, seqitem[0], seqitem[1])

      ## Inserts or Updates a key-value pair in the database
      db["test6"] = "test6value"
      value = db["test6"]

      ## Returns of the most recent error encountered when operating on the database dbf
      errl = db.LastError()
      debugEcho "db[test6]=", value, " errl:", $errl

      ## Counts number of records in the database dbf
      let ucnt = db.Count()
      debugEcho "db.Count:", $ucnt

      for pair in db.keyValueIterator():
        stdout.writeLine(pair)

      for key in db.keyIterator():
        stdout.writeLine(key)

For ditails see block test: in gdbmc.nim

Example: memory efficient deduplication for files

    import gdbmc
    from system import quit
    from os import getFileInfo
    from re import re, replace
    from strutils import strip
    from md5 import getMD5

    block:
      let stdin_info = getFileInfo(stdin)
      if stdin_info.id.file == 9:
        echo "Use: cat file.txt|deduplicate"
        quit 1

      const filename: string = "/tmp/dedup-nim.db"
      let
        db = Open(filename, "n")
      defer: Close(db)
      var line = ""
      while stdin.readLine(line):
        line = line.strip.replace(re"(\s+)", " ")
        let md5line = getMD5(line)
        if md5line notin db:
          db[md5line] = ""
          echo line

License

MIT License. You may use any compatible license (essentially any license) for your own programs developed with gdbmc

gdbmc.nim's Issues

Fetch method result

Hi!, I've tried this library, but frequently it doesn't work. (Example: memory efficient deduplication for files). I'm using Linux Mint 20.3 (x64).
I think it's because the Fetch method, FirstKey, and NextKey don't come with the last null character in the returned string.
The original c language gdbm, either store it with last '\0', or look at dsize and copy it somewhere. Maybe it doesn't have to be a string.

if vdatum.dptr == nil:
    result = ""
else:
    result = newString(vdatum.dsize)
    copyMem(result[0].addr, vdatum.dptr, vdatum.dsize)

This will work always...