Mercurial > hg > truffle
diff src/share/vm/utilities/hashtable.cpp @ 20493:152cf4afc11f
8056084: Refactor Hashtable to allow implementations without rehashing support
Reviewed-by: gziemski, jmasa, brutisso, coleenp, tschatzl
author | mgerdin |
---|---|
date | Fri, 29 Aug 2014 13:08:01 +0200 |
parents | f9e35a9dc8c7 |
children | 7baf47cb97cb |
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--- a/src/share/vm/utilities/hashtable.cpp Tue Sep 23 17:24:34 2014 -0700 +++ b/src/share/vm/utilities/hashtable.cpp Fri Aug 29 13:08:01 2014 +0200 @@ -36,21 +36,22 @@ #include "utilities/numberSeq.hpp" -// This is a generic hashtable, designed to be used for the symbol -// and string tables. -// -// It is implemented as an open hash table with a fixed number of buckets. -// -// %note: -// - HashtableEntrys are allocated in blocks to reduce the space overhead. +// This hashtable is implemented as an open hash table with a fixed number of buckets. -template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) { - BasicHashtableEntry<F>* entry; - - if (_free_list) { +template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry_free_list() { + BasicHashtableEntry<F>* entry = NULL; + if (_free_list != NULL) { entry = _free_list; _free_list = _free_list->next(); - } else { + } + return entry; +} + +// HashtableEntrys are allocated in blocks to reduce the space overhead. +template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) { + BasicHashtableEntry<F>* entry = new_entry_free_list(); + + if (entry == NULL) { if (_first_free_entry + _entry_size >= _end_block) { int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries)); int len = _entry_size * block_size; @@ -83,9 +84,9 @@ // This is somewhat an arbitrary heuristic but if one bucket gets to // rehash_count which is currently 100, there's probably something wrong. -template <MEMFLAGS F> bool BasicHashtable<F>::check_rehash_table(int count) { - assert(table_size() != 0, "underflow"); - if (count > (((double)number_of_entries()/(double)table_size())*rehash_multiple)) { +template <class T, MEMFLAGS F> bool RehashableHashtable<T, F>::check_rehash_table(int count) { + assert(this->table_size() != 0, "underflow"); + if (count > (((double)this->number_of_entries()/(double)this->table_size())*rehash_multiple)) { // Set a flag for the next safepoint, which should be at some guaranteed // safepoint interval. return true; @@ -93,13 +94,13 @@ return false; } -template <class T, MEMFLAGS F> juint Hashtable<T, F>::_seed = 0; +template <class T, MEMFLAGS F> juint RehashableHashtable<T, F>::_seed = 0; // Create a new table and using alternate hash code, populate the new table // with the existing elements. This can be used to change the hash code // and could in the future change the size of the table. -template <class T, MEMFLAGS F> void Hashtable<T, F>::move_to(Hashtable<T, F>* new_table) { +template <class T, MEMFLAGS F> void RehashableHashtable<T, F>::move_to(RehashableHashtable<T, F>* new_table) { // Initialize the global seed for hashing. _seed = AltHashing::compute_seed(); @@ -109,7 +110,7 @@ // Iterate through the table and create a new entry for the new table for (int i = 0; i < new_table->table_size(); ++i) { - for (HashtableEntry<T, F>* p = bucket(i); p != NULL; ) { + for (HashtableEntry<T, F>* p = this->bucket(i); p != NULL; ) { HashtableEntry<T, F>* next = p->next(); T string = p->literal(); // Use alternate hashing algorithm on the symbol in the first table @@ -238,11 +239,11 @@ } } -template <class T, MEMFLAGS F> int Hashtable<T, F>::literal_size(Symbol *symbol) { +template <class T, MEMFLAGS F> int RehashableHashtable<T, F>::literal_size(Symbol *symbol) { return symbol->size() * HeapWordSize; } -template <class T, MEMFLAGS F> int Hashtable<T, F>::literal_size(oop oop) { +template <class T, MEMFLAGS F> int RehashableHashtable<T, F>::literal_size(oop oop) { // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true, // and the String.value array is shared by several Strings. However, starting from JDK8, // the String.value array is not shared anymore. @@ -255,12 +256,12 @@ // Note: if you create a new subclass of Hashtable<MyNewType, F>, you will need to // add a new function Hashtable<T, F>::literal_size(MyNewType lit) -template <class T, MEMFLAGS F> void Hashtable<T, F>::dump_table(outputStream* st, const char *table_name) { +template <class T, MEMFLAGS F> void RehashableHashtable<T, F>::dump_table(outputStream* st, const char *table_name) { NumberSeq summary; int literal_bytes = 0; for (int i = 0; i < this->table_size(); ++i) { int count = 0; - for (HashtableEntry<T, F>* e = bucket(i); + for (HashtableEntry<T, F>* e = this->bucket(i); e != NULL; e = e->next()) { count++; literal_bytes += literal_size(e->literal()); @@ -270,7 +271,7 @@ double num_buckets = summary.num(); double num_entries = summary.sum(); - int bucket_bytes = (int)num_buckets * sizeof(bucket(0)); + int bucket_bytes = (int)num_buckets * sizeof(HashtableBucket<F>); int entry_bytes = (int)num_entries * sizeof(HashtableEntry<T, F>); int total_bytes = literal_bytes + bucket_bytes + entry_bytes; @@ -353,11 +354,14 @@ #endif // Explicitly instantiate these types template class Hashtable<ConstantPool*, mtClass>; +template class RehashableHashtable<Symbol*, mtSymbol>; +template class RehashableHashtable<oopDesc*, mtSymbol>; template class Hashtable<Symbol*, mtSymbol>; template class Hashtable<Klass*, mtClass>; template class Hashtable<oop, mtClass>; #if defined(SOLARIS) || defined(CHECK_UNHANDLED_OOPS) template class Hashtable<oop, mtSymbol>; +template class RehashableHashtable<oop, mtSymbol>; #endif // SOLARIS || CHECK_UNHANDLED_OOPS template class Hashtable<oopDesc*, mtSymbol>; template class Hashtable<Symbol*, mtClass>;