Jeannie: Granting Java Native Interface Developers their Wishes

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Jeannie Granting Java Native Interface
Developers their Wishes
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FFI Foreign Function Interface
UserProgram nqueens
BrownJava
StandardLibraries java.io
CustomLibraries JavaBDD

• Motivation
• OS Services
• Legacy Code
• Performance
• Convenience

Virtual Execution Environment JVM
Operating System Linux
BlueC
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JNI Java Native Interface
Java
Native methodno body in Java
C function with mangled nameimplements Java
method
C
Read Javafield from C
Throw Javaexception from C
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FFI Design Goals

• Productivity
• Writing maintaining code
• Safety
• Preventing detecting bugs
• Efficiency
• At transition elsewhere
• Portability
• Different OS, HW, virtual execution environment

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Jeannie Example
Support fullC syntax
Can useshort names
Native methods have a body
Nestedblock
Nestedexpression
Can nest toany depth
Exception handling in C
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Jeannie Build Process
Socket.jni
Preprocessor
Socket.jni.i
Jeannie Compiler
Java sources
C sources
Socket.i
Socket.java
Java Compiler
C Compiler
Network.jar
Network.dll
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Translation Scheme
Jeannie source code
Generated code
class JavaEnv int x int z native m1()
m2(CEnv) native m3(CEnv) m4(CEnv) struct
CEnv jint yJava_C_m1(JEnv) Java_C_m3(JEnv,
CEnv)
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Typing

• Nested expressions have equivalent types
• if (((jboolean)feof(stdin))) ..
• Java references are opaque in C
• Use in nested Java expression
• Assign to variable
• Pass as parameter
• Return as result
• C can widen Java references
• List lst new ArrayList(10)
• C pointers/structs/unions are illegal in Java

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Java Garbage Collection
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Compiler Stages
Jeannie code
Jeannie grammar
Jeannie Parser
Jeannie AST
Jeannie Analyzer
Jeannie ASTSymTab
Code generator
C code
Java code
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Scalable Composition Syntax
Jeannie code
C grammar
Rats!parsergenerator
Jeannie Parser
Jeannie grammar
Java grammar
Jeannie AST
Jeannie Analyzer
Jeannie ASTSymTab
Code generator
C code
Java code
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Scalable Composition Analyzers
Jeannie code
C grammar
Rats!parsergenerator
Jeannie Parser
Jeannie grammar
Java grammar
Jeannie AST
xtc visitors,commontype rep.
C Jeannie Java Analyzer
Jeannie ASTSymTab
Code generator
C code
Java code
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Scalable Composition CodeGen
Jeannie code
C grammar
Rats!parsergenerator
Jeannie Parser
Jeannie grammar
Java grammar
Jeannie AST
xtc visitors,commontype rep.
C Jeannie Java Analyzer
Jeannie ASTSymTab
xtc ASTgenerator
Code generator
Java stencils
C stencils
C AST
Java AST
C pretty printer
Java pretty printer
C code
Java code
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FFI Design Goals Revisited

• Productivity
• Concise syntax
• Safety
• Static error checking
• Efficiency
• See next slide
• Portability
• Java virtual machines HotSpot, J9, Jikes RVM
• Operating systems Mac OS X, Linux, Cygwin

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Efficiency JNI vs. Jeannie
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Array Access

• Nested expression is simple
• for (i 0, n ja.length i lt n i)
• s jai

• But bulk access is faster
• with (jint ca ja)
• jint n ja.length
• for (jint i0 iltn i)
• s cai

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EfficiencyBulk vs. Simple Array Access
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Related Work

• Improving JNI
• Productivity BubakKurzyniec (Janet)
• Safety Tan et al. (Ccured, ILEA),FurrFoster
  (type inference)
• Efficiency Stepanian et al. (JIT native code)
• Portability Chen et al. (dynamic binary
  translator)
• Deep language interoperability
• XJ, XTATIC, C?, Linq, DALI
• Scalable composition
• Polyglot, JastAdd, Silver, Stratego/XT, Safari

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Conclusions

• Have
• Language Jeannie FFI(JavaC)
• Open source compiler contributed to xtc
  http//cs.nyu.edu/rgrimm/xtc
• Next
• Debugging
• Fault isolation
• Optimization