When trying to create an array class, we try to resolve
java.lang.Object so we can use its vtable in the array class.
However, if Object is missing, we'll try to create and throw a
ClassNotFoundException, which requires creating an array to store the
stack trace, which requires creating an array class, which requires
resolving Object, etc.. This commit short-circuits this process by
telling resolveClass not to create and throw an exception if it can't
find Object.
While doing the above work, I noticed that the implementations of
Classpath::makeThrowable in classpath-avian.cpp and
classpath-openjdk.cpp were identical, so I made makeThrowable a
top-level function.
Finally, I discovered that Thread.setDaemon can only be called before
the target thread has been started, which allowed me to simplify the
code to track daemon threads in the VM.
This mainly involves some makefile ugliness to work around bugs in the
native Windows OpenJDK code involving conflicting static and
not-static declarations which GCC 4.0 and later justifiably reject but
MSVC tolerates.
* add libnet.so and libnio.so to built-in libraries for openjdk-src build
* implement sun.misc.Unsafe.park/unpark
* implement JVM_SetClassSigners/JVM_GetClassSigners
* etc.
The main change here is to use a lazily-populated vector to associate
runtime data with classes instead of referencing them directly from
the class which requires updating immutable references in the heap
image. The other changes employ other strategies to avoid trying to
update immutable references.
All the tests are passing for openjdk-src builds, but the non-src
openjdk build is crashing and there's trouble loading time zone info
from the embedded java.home directory.
This allows OpenJDK to access time zone data which is normally found
under java.home, but which we must embed in the executable itself to
create a self-contained build. The VM intercepts various file
operations, looking for paths which start with a prefix specified by
the avian.embed.prefix property and redirecting those operations to an
embedded JAR.
For example, if avian.embed.prefix is "/avian-embedded", and code
calls File.exists() with a path of
"/avian-embedded/javahomeJar/foo.txt", the VM looks for a function
named javahomeJar via dlsym, calls the function to find the memory
region containing the embeded JAR, and finally consults the JAR to see
if the file "foo.txt" exists.
sun.misc.Unsafe.getUnsafe expects a null result if the class loader is
the boot classloader and will throw a SecurityException otherwise
(whereas it should really be checking both for null and comparing
against the system classloader). However, just returning null
whenever the loader is the boot loader can cause trouble for embedded
apps which put everything in the boot loader, including application
resources.
Therefore, we only return null if it's the boot loader and we're being
called from Unsafe.getUnsafe.
As described in readme.txt, a standalone OpenJDK build embeds all
libraries, classes, and other files needed at runtime in the resulting
binary, eliminating dependencies on external resources.
We now consult the JAVA_HOME environment variable to determine where
to find the system library JARs and SOs. Ultimately, we'll want to
support self-contained build, but this allows Avian to behave like a
conventional libjvm.so.
The main changes in this commit ensure that we don't hold the global
class lock when doing class resolution using application-defined
classloaders. Such classloaders may do their own locking (in fact,
it's almost certain), making deadlock likely when mixed with VM-level
locking in various orders.
Other changes include a fix to avoid overflow when waiting for
extremely long intervals and a GC root stack mapping bug.
The biggest change in this commit is to split the system classloader
into two: one for boot classes (e.g. java.lang.*) and another for
application classes. This is necessary to make OpenJDK's security
checks happy.
The rest of the changes include bugfixes and additional JVM method
implementations in classpath-openjdk.cpp.
Whereas the GNU Classpath port used the strategy of patching Classpath
with core classes from Avian so as to minimize changes to the VM, this
port uses the opposite strategy: abstract and isolate
classpath-specific features in the VM similar to how we abstract away
platform-specific features in system.h. This allows us to use an
unmodified copy of OpenJDK's class library, including its core classes
and augmented by a few VM-specific classes in the "avian" package.
