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dotnet framework : String -> StringBuilder Optimization
OK, I can't figure out a way to optimize the following VB 2005 code using
StringBuilders: Public Const RecSize as Integer = 105 Private buffer As String Public Sub New() init End Sub Public Sub New(ByVal value As String) buffer = LSet(value, 105) End Sub Public Sub init() buffer = Space(105) End Sub Private Function fetch(ByVal start As Integer, ByVal chars As Integer) As String fetch = Mid(buffer, start, chars) End Function Private Sub putch(ByRef s As String, ByVal start As Integer, ByVal chars As Integer) Mid(buffer, start, chars) = LSet(s, chars) End Sub Public Property BUF() as String Get Return fetch(1, 105) End Get Set(ByVal value as string) putch(value, 1, 105) End Set End Property Public Property KEY0() as String Get Return fetch(1, 19) End Get Set(ByVal value as string) putch(value, 1, 19) End Set End Property ' Additional fields are also defined in the same manner. The public interface to this class must remain as strings, but I'd like to optimize the implementation. Note that this is a sample from our interface to a VMS BASIC environment and this code is actually being generated by a VB 6 program from the VMS Record Management Services (RMS) definition files. Once a data record is in this object, I need to be able to change it, but don't want to drive the GC nuts allocating/deallocating the internal buffer string. For each class, the total length of buffer is fixed. I can't use a simple record because RMS allows overlapping variants and the VB 6 program has been coded to support that. Mike Ober.
So far, no performance issues, but it's used a lot - as in every single
field in our database runs through this type of code. Some of the tables have over 100 fields (I didn't design it - I just have to live with it). Mike. [quoted text, click to view] "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in message news:efjiaj$i0b$1$8302bc10@news.demon.co.uk... > > "Michael D. Ober" <obermd.@.alum.mit.edu.nospam> wrote in message > news:uwE14894GHA.4196@TK2MSFTNGP03.phx.gbl... >> OK, I can't figure out a way to optimize the following VB 2005 code using >> StringBuilders: > > Can I ask a simple question? Are you experiencing performance problems > with this piece of code? Is it slow, or eating up all of your available > memory or something nasty like that? >
[quoted text, click to view] Michael D. Ober wrote: > OK, I can't figure out a way to optimize the following VB 2005 code using > StringBuilders: > I don't think I would use a StringBuilder here. Maybe just a plain old char array along with Buffer.BlockCopy. Strings could still be returned when needed - just pass a char array to the string constructor. -- Tom Shelton
[quoted text, click to view] "Michael D. Ober" <obermd.@.alum.mit.edu.nospam> wrote in message news:uwE14894GHA.4196@TK2MSFTNGP03.phx.gbl... > OK, I can't figure out a way to optimize the following VB 2005 code using > StringBuilders: Can I ask a simple question? Are you experiencing performance problems with this piece of code? Is it slow, or eating up all of your available memory or something nasty like that?
Hi Michael,
If you haven't experienced any issues then you might not want to concern yourself with modifying code that works, as I believe Robinson was suggesting by asking questions related to the performance of your design, but I do understand if you only want to perform some simple optimizations ahead of time. That said, have you thought about using a StringDictionary instead of a StringBuilder or string buffer? You might want to just parse the complete input string once, or parse each field on-demand and store the references to each of the fields' values in case they are recalled at a later time. If you can design the class so that the parsing of each field is only done once then a StringBuilder would be of no use, unless of course you need to rebuild the buffer for output with new values. It might be cheaper to simply rebuild the buffer on-demand then it would be to perform string manipulation in each properties' get/set accessor, but that of course depends on the number of property read/writes compared to the number of times your class will need to rebuild the buffer for output and the actual tasks performed by each operation. I think, without those statistics, that parsing in the get/set accessors each time will probably have an increased negative effect on your application's performance and the GC more than if you were to cache the fields values in a StringDictionary and simply get/set them when required. HTH -- Dave Sexton [quoted text, click to view] "Michael D. Ober" <obermd.@.alum.mit.edu.nospam> wrote in message news:uwE14894GHA.4196@TK2MSFTNGP03.phx.gbl... > OK, I can't figure out a way to optimize the following VB 2005 code using StringBuilders: > > Public Const RecSize as Integer = 105 > Private buffer As String > > Public Sub New() > init > End Sub > Public Sub New(ByVal value As String) > buffer = LSet(value, 105) > End Sub > > Public Sub init() > buffer = Space(105) > End Sub > > Private Function fetch(ByVal start As Integer, ByVal chars As Integer) As String > fetch = Mid(buffer, start, chars) > End Function > Private Sub putch(ByRef s As String, ByVal start As Integer, ByVal chars As Integer) > Mid(buffer, start, chars) = LSet(s, chars) > End Sub > > Public Property BUF() as String > Get > Return fetch(1, 105) > End Get > Set(ByVal value as string) > putch(value, 1, 105) > End Set > End Property > > Public Property KEY0() as String > Get > Return fetch(1, 19) > End Get > Set(ByVal value as string) > putch(value, 1, 19) > End Set > End Property > > ' Additional fields are also defined in the same manner. > > The public interface to this class must remain as strings, but I'd like to optimize the implementation. Note that this is a > sample from our interface to a VMS BASIC environment and this code is actually being generated by a VB 6 program from the VMS > Record Management Services (RMS) definition files. Once a data record is in this object, I need to be able to change it, but don't > want to drive the GC nuts allocating/deallocating the internal buffer string. For each class, the total length of buffer is > fixed. I can't use a simple record because RMS allows overlapping variants and the VB 6 program has been coded to support that. > > Mike Ober. > >
Michael,
I think using something else than as the code is now, will influence the performance. It will in my idea go slower. Cor "Michael D. Ober" <obermd.@.alum.mit.edu.nospam> schreef in bericht news:uwE14894GHA.4196@TK2MSFTNGP03.phx.gbl... [quoted text, click to view] > OK, I can't figure out a way to optimize the following VB 2005 code using > StringBuilders: > > Public Const RecSize as Integer = 105 > Private buffer As String > > Public Sub New() > init > End Sub > Public Sub New(ByVal value As String) > buffer = LSet(value, 105) > End Sub > > Public Sub init() > buffer = Space(105) > End Sub > > Private Function fetch(ByVal start As Integer, ByVal chars As Integer) As > String > fetch = Mid(buffer, start, chars) > End Function > Private Sub putch(ByRef s As String, ByVal start As Integer, ByVal chars > As Integer) > Mid(buffer, start, chars) = LSet(s, chars) > End Sub > > Public Property BUF() as String > Get > Return fetch(1, 105) > End Get > Set(ByVal value as string) > putch(value, 1, 105) > End Set > End Property > > Public Property KEY0() as String > Get > Return fetch(1, 19) > End Get > Set(ByVal value as string) > putch(value, 1, 19) > End Set > End Property > > ' Additional fields are also defined in the same manner. > > The public interface to this class must remain as strings, but I'd like to > optimize the implementation. Note that this is a sample from our > interface to a VMS BASIC environment and this code is actually being > generated by a VB 6 program from the VMS Record Management Services (RMS) > definition files. Once a data record is in this object, I need to be able > to change it, but don't want to drive the GC nuts allocating/deallocating > the internal buffer string. For each class, the total length of buffer is > fixed. I can't use a simple record because RMS allows overlapping > variants and the VB 6 program has been coded to support that. > > Mike Ober. > >
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