Mailing-List: contact dev-help@harmony.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@harmony.apache.org
Received-SPF: pass (athena.apache.org: domain of gshimansky@gmail.com
 designates 64.233.184.239 as permitted sender)
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=message-id:date:from:user-agent:mime-version:to:subject:references:in-reply-to:content-type:content-transfer-encoding:sender;
        b=eu9Ze1SkHaSFE/4SInZyFHwycVOd4QCbl/y+pfoQ3OyKgau3J1yeowZvGwzzn5Op/JE3umvmBNBvsa50iM4oi3vLGJU1PhSp2Z1D4ZROlVVDYjFW7tk7eYkHQrmUp5E2kpzgGorJROpwnvi0c7COA+OOFUsJG0yxd+ipFLExhqA=
Message-ID: <47C3DE58.4040100@apache.org>
Date: Tue, 26 Feb 2008 12:39:36 +0300
From: Gregory Shimansky <gshimansky@apache.org>
User-Agent: Thunderbird 2.0.0.9 (Windows/20071031)
MIME-Version: 1.0
To: dev@harmony.apache.org
Subject: Re: [jdktools][JDWP]using portlib to support JDWP transport/agent?
References: <5c8e69f0802242256x4a907e93k3ee9b7ce8a966755@mail.gmail.com>
	 <b6cb498e0802252014n9d21ab7v7c5fb08f1450e5e8@mail.gmail.com>
 <5c8e69f0802260115y226ad9b8t7db5d745bcbf172@mail.gmail.com>
In-Reply-To: <5c8e69f0802260115y226ad9b8t7db5d745bcbf172@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: Gregory Shimansky <gshimansky@gmail.com>

Jimmy,Jing Lv said the following on 26.02.2008 12:15:
> Hi,
> 
> 2008/2/26, Ivan Popov <ivan.g.popov@gmail.com>:
>> JDWP agent and transport implementation was developed independent on
>>  Harmony's drlvm and classlib implementations in order to be run easily
>>  on top on any JVM. That's why it does not use any portlib support for
>>  platform dependent code.
>>
>>  I agree, however, it would be better to re-use platform dependent
>>  support from portlib to facilitate porting jdwp code to other
>>  platforms. The only such code is TCP/IP sockets api used in dt_socket
>>  transport and loading transport DLL in the agent itself. All other
>>  code is based on standard JVMTI api and thus is platform independent.
>>
> 
> I notice the DLL loading as well. I have an idea here that shall we
> start with java-level lib loading process? For Java code it may be
> quite easy to do such work as:
>      System.loadLibrary("libname");
> 
> We can do similar things. What does native code do in this
> "System.loadLibrary", does vm/classlib native code support such API
> for work? If so, we may
> 1) directly call that API  to load lib and avoid  platform differences
> If no, we may
> 2) create a java class to do the such work, reflect in the native
> TransportManager. Though it may be a little strange and slower in
> performance, it may also works.
> 
> Any VM guru know what's happening in the System.loadLibrary()? Would
> it be used without java-level call?

I am not sure that using Java is possible here. First, agent's 
initialization happens in ON_LOAD phase [1] where VM doesn't allow to 
execute any Java code yet.

Second, even if you make a call to System.loadLibrary (Java or 
underlying native function) you'd need the library handle to obtain 
(with a platform dependent function) function pointers from it.

[1] http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#GetPhase

-- 
Gregory