"hash_iter_lev" can be exported by Marshal.dump and it will
introduce inconsistency. To avoid this issue, use internal_id
instead of normal ID. This issue is pointed out by Chikanaga-san.
On ar_table, Do not keep a full-length hash value (FLHV, 8 bytes)
but keep a 1 byte hint from a FLHV (lowest byte of FLHV).
An ar_table only contains at least 8 entries, so hints consumes
8 bytes at most. We can store hints in RHash::ar_hint.
On 32bit CPU, we use 4 entries ar_table.
The advantages:
* We don't need to keep FLHV so ar_table only consumes
16 bytes (VALUEs of key and value) * 8 entries = 128 bytes.
* We don't need to scan ar_table, but only need to check hints
in many cases. Especially we don't need to access ar_table
if there is no match entries (in many cases).
It will increase memory cache locality.
The disadvantages:
* This technique can increase `#eql?` time because hints can
conflicts (in theory, it conflicts once in 256 times).
It can introduce incompatibility if there is a object x where
x.eql? returns true even if hash values are different.
I believe we don't need to care such irregular case.
* We need to re-calculate FLHV if we need to switch from ar_table
to st_table (e.g. exceeds 8 entries).
It also can introduce incompatibility, on mutating key objects.
I believe we don't need to care such irregular case too.
Add new debug counters to measure the performance:
* artable_hint_hit - hint is matched and eql?#=>true
* artable_hint_miss - hint is not matched but eql?#=>false
* artable_hint_notfound - lookup counts
iter_lev is used to detect the hash is iterating or not.
Usually, iter_lev should be very small number (1 or 2) so
`int` is overkill.
This patch introduce iter_lev in flags (7 bits, FL13 to FL19)
and if iter_lev exceeds this range, save it in hidden attribute.
We can get 1 word in RHash.
We can't modify frozen objects. Therefore I added new internal API
`rb_ivar_set_internal()` which allows us to set an attribute
even if the target object is frozen
if the name is hidden ivar (the name without `@` prefix).
The behavior of `Hash[[nil]] #=> {}` was a bug until 1.9.3, but had been
remained with a warning because some programs depended upon it.
Now, six years passed. We can remove the compatibility behavior.
[Bug #7300]
For example when an array containing objects is a hash key, the contents
of the array may move which can cause the hash value for the array to
change. This commit makes the default `hash` value based off the
object id, so the hash value will remain stable.
Fixes test/shell/test_command_processor.rb
For some reason symbols (or classes) are being overridden in trunk
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67598 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit adds the new method `GC.compact` and compacting GC support.
Please see this issue for caveats:
https://bugs.ruby-lang.org/issues/15626
[Feature #15626]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67576 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Because hard to specify commits related to r67479 only.
So please commit again.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67499 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit adds the new method `GC.compact` and compacting GC support.
Please see this issue for caveats:
https://bugs.ruby-lang.org/issues/15626
[Feature #15626]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67479 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c (RHASH_AR_TABLE_SIZE_DEC): generally, we need to check all
entries to calculate exact "bound" in ar_table, but if size == 0,
we can clear bound because there are no active entries.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66843 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c: ar_table only supports `objhash` so we can call compare/hash
functions directly.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66718 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c (hash_stlike_lookup): introduce inline a function and use it
instead of using ar_lookup()/st_lookup() directly.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66717 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c: the type of `ar_table_entry::hash` is not a `VALUE`,
but a `st_hash_t`.
Also `st_hash_t` is not a `st_data_t`, but `st_index_t` (same as st.c).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66700 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* internal.h: move ar_table def to hash.c because other files
don't need to know implementation of ar_table.
* hash.c (rb_hash_ar_table_size): added because gc.c needs to know
the size_of(ar_table).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66638 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c: separate NULL and EMPTY check functions.
`RHASH_TABLE_EMPTY` function checks NULL table or not,
but it should be named "NULL_P".
Introduce `RHASH_TABLE_EMPTY_P` function to check size == 0.
There are cases that hash has table data even if data is not NULL
(in case removed after inserted elements).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66392 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* internal.h: rename the following names:
* li_table -> ar_table. "li" means linear (from linear search),
but we use the word "array" (from data layout).
* RHASH_ARRAY -> RHASH_AR_TABLE. AR_TABLE is more clear.
* rb_hash_array_* -> rb_hash_ar_table_*.
* RHASH_TABLE_P() -> RHASH_ST_TABLE_P(). more clear.
* RHASH_CLEAR() -> RHASH_ST_CLEAR().
* hash.c: rename "linear_" prefix functions to "ar_" prefix.
* hash.c (linear_init_table): rename to ar_alloc_table.
* debug_counter.h: rename obj_hash_array to obj_hash_ar.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66390 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* hash.c (linear_update): initialize `bin` just to silence false
warnings by old gcc 4.8. [Bug #15299]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66306 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
The reserved hash values in hash.c must be consistend with st.c.
[ruby-core:90356] [Bug #15389]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66274 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
