drop heap page support for Ruby <= 3.0

Ruby 3.1 uses mmap, nowadays, and I don't think it's worth the
effort to suport it since mmap and munmap don't require the
symmetry *memalign + free do.

4 files changed, 12 insertions, 411 deletions

diff --git a/ext/mwrap/extconf.rb b/ext/mwrap/extconf.rb
index 1828407..e8d3cc6 100644
--- a/ext/mwrap/extconf.rb
+++ b/ext/mwrap/extconf.rb
@@ -25,11 +25,4 @@ else
   abort 'missing __builtin_add_overflow'
 end
 
-begin
-  if n = GC::INTERNAL_CONSTANTS[:HEAP_PAGE_SIZE]
-    $defs << "-DHEAP_PAGE_SIZE=#{n}"
-  end
-rescue NameError
-end
-
 create_makefile 'mwrap'
diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c
index 08761d6..6875486 100644
--- a/ext/mwrap/mwrap.c
+++ b/ext/mwrap/mwrap.c
@@ -51,19 +51,6 @@ static size_t total_bytes_inc, total_bytes_dec;
 /* true for glibc/dlmalloc/ptmalloc, not sure about jemalloc */
 #define ASSUMED_MALLOC_ALIGNMENT (sizeof(void *) * 2)
 
-/* match values in Ruby gc.c */
-#define HEAP_PAGE_ALIGN_LOG 14
-enum {
-        HEAP_PAGE_ALIGN = (1UL << HEAP_PAGE_ALIGN_LOG)
-#ifndef HEAP_PAGE_SIZE /* Ruby 2.6-2.7 only */
-        ,
-        REQUIRED_SIZE_BY_MALLOC = (sizeof(size_t) * 5),
-        HEAP_PAGE_SIZE = (HEAP_PAGE_ALIGN - REQUIRED_SIZE_BY_MALLOC)
-#endif
-};
-
-#define IS_HEAP_PAGE_BODY ((struct src_loc *)-1)
-
 #ifdef __FreeBSD__
 void *__malloc(size_t);
 void __free(void *);
@@ -111,33 +98,6 @@ static union padded_mutex mutexes[MUTEX_NR] = {
 #endif
 };
 
-#define ACC_INIT(name) { .nr=0, .min=INT64_MAX, .max=-1, .m2=0, .mean=0 }
-struct acc {
-        uint64_t nr;
-        int64_t min;
-        int64_t max;
-        double m2;
-        double mean;
-};
-
-/* for tracking 16K-aligned heap page bodies (protected by GVL) */
-struct {
-        pthread_mutex_t lock;
-        struct cds_list_head bodies;
-        struct cds_list_head freed;
-
-        struct acc alive;
-        struct acc reborn;
-} hpb_stats = {
-#if STATIC_MTX_INIT_OK
-        .lock = PTHREAD_MUTEX_INITIALIZER,
-#endif
-        .bodies = CDS_LIST_HEAD_INIT(hpb_stats.bodies),
-        .freed = CDS_LIST_HEAD_INIT(hpb_stats.freed),
-        .alive = ACC_INIT(hpb_stats.alive),
-        .reborn = ACC_INIT(hpb_stats.reborn)
-};
-
 static pthread_mutex_t *mutex_assign(void)
 {
         return &mutexes[uatomic_add_return(&mutex_i, 1) & MUTEX_MASK].mtx;
@@ -168,11 +128,6 @@ __attribute__((constructor)) static void resolve_malloc(void)
                                 _exit(1);
                         }
                 }
-                err = pthread_mutex_init(&hpb_stats.lock, 0);
-                if (err) {
-                        fprintf(stderr, "error: %s\n", strerror(err));
-                        _exit(1);
-                }
                 /* initialize mutexes used by urcu-bp */
                 rcu_read_lock();
                 rcu_read_unlock();
@@ -300,9 +255,6 @@ struct alloc_hdr {
                         struct src_loc *loc;
                 } live;
                 struct rcu_head dead;
-                struct {
-                        size_t at; /* rb_gc_count() */
-                } hpb_freed;
         } as;
         void *real; /* what to call real_free on */
         size_t size;
@@ -344,64 +296,6 @@ static int loc_eq(struct cds_lfht_node *node, const void *key)
                 memcmp(k->k, existing->k, loc_size(k)) == 0);
 }
 
-/* note: not atomic */
-static void
-acc_add(struct acc *acc, size_t val)
-{
-        double delta = val - acc->mean;
-        uint64_t nr = ++acc->nr;
-
-        /* just don't divide-by-zero if we ever hit this (unlikely :P) */
-        if (nr)
-                acc->mean += delta / nr;
-
-        acc->m2 += delta * (val - acc->mean);
-        if ((int64_t)val < acc->min)
-                acc->min = (int64_t)val;
-        if ((int64_t)val > acc->max)
-                acc->max = (int64_t)val;
-}
-
-#if SIZEOF_LONG == 8
-# define INT64toNUM(x) LONG2NUM((long)x)
-#elif defined(HAVE_LONG_LONG) && SIZEOF_LONG_LONG == 8
-# define INT64toNUM(x) LL2NUM((LONG_LONG)x)
-#endif
-
-static VALUE
-acc_max(const struct acc *acc)
-{
-        return INT64toNUM(acc->max);
-}
-
-static VALUE
-acc_min(const struct acc *acc)
-{
-        return acc->min == INT64_MAX ? INT2FIX(-1) : INT64toNUM(acc->min);
-}
-
-static VALUE
-acc_mean(const struct acc *acc)
-{
-        return DBL2NUM(acc->nr ? acc->mean : HUGE_VAL);
-}
-
-static double
-acc_stddev_dbl(const struct acc *acc)
-{
-        if (acc->nr > 1) {
-                double variance = acc->m2 / (acc->nr - 1);
-                return sqrt(variance);
-        }
-        return 0.0;
-}
-
-static VALUE
-acc_stddev(const struct acc *acc)
-{
-        return DBL2NUM(acc_stddev_dbl(acc));
-}
-
 static struct src_loc *totals_add_rcu(const struct src_loc *k)
 {
         struct cds_lfht_iter iter;
@@ -519,7 +413,7 @@ void free(void *p)
                 struct src_loc *l = h->as.live.loc;
 
                 if (!real_free) return; /* oh well, leak a little */
-                if (l && l != IS_HEAP_PAGE_BODY) {
+                if (l) {
                         size_t age = generation - h->as.live.gen;
 
                         uatomic_add(&total_bytes_dec, h->size);
@@ -534,19 +428,6 @@ void free(void *p)
                         mutex_unlock(l->mtx);
 
                         call_rcu(&h->as.dead, free_hdr_rcu);
-                } else if (l == IS_HEAP_PAGE_BODY) {
-                        size_t gen = generation;
-                        size_t age = gen - h->as.live.gen;
-
-                        h->as.hpb_freed.at = gen;
-
-                        mutex_lock(&hpb_stats.lock);
-                        acc_add(&hpb_stats.alive, age);
-
-                        /* hpb_stats.bodies => hpb_stats.freed */
-                        cds_list_move(&h->anode, &hpb_stats.freed);
-
-                        mutex_unlock(&hpb_stats.lock);
                 } else {
                         real_free(h->real);
                 }
@@ -614,65 +495,18 @@ internal_memalign(void **pp, size_t alignment, size_t size, uintptr_t caller)
                 return ENOMEM;
 
 
-        if (alignment == HEAP_PAGE_ALIGN && size == HEAP_PAGE_SIZE) {
-                if (has_ec_p()) generation = rb_gc_count();
-                l = IS_HEAP_PAGE_BODY;
-        } else {
-                l = update_stats_rcu_lock(size, caller);
-        }
+        l = update_stats_rcu_lock(size, caller);
 
-        if (l == IS_HEAP_PAGE_BODY) {
-                void *p;
-                size_t gen = generation;
-
-                mutex_lock(&hpb_stats.lock);
-
-                /* reuse existing entry */
-                if (!cds_list_empty(&hpb_stats.freed)) {
-                        size_t deathspan;
-
-                        h = cds_list_first_entry(&hpb_stats.freed,
-                                                 struct alloc_hdr, anode);
-                        /* hpb_stats.freed => hpb_stats.bodies */
-                        cds_list_move(&h->anode, &hpb_stats.bodies);
-                        assert(h->size == size);
-                        assert(h->real);
-                        real = h->real;
-                        p = hdr2ptr(h);
-                        assert(ptr_is_aligned(p, alignment));
-
-                        deathspan = gen - h->as.hpb_freed.at;
-                        acc_add(&hpb_stats.reborn, deathspan);
-                }
-                else {
-                        real = real_malloc(asize);
-                        if (!real) return ENOMEM;
-
-                        p = hdr2ptr(real);
-                        if (!ptr_is_aligned(p, alignment))
-                                p = ptr_align(p, alignment);
-                        h = ptr2hdr(p);
-                        h->size = size;
-                        h->real = real;
-                        cds_list_add(&h->anode, &hpb_stats.bodies);
-                }
-                mutex_unlock(&hpb_stats.lock);
-                h->as.live.loc = l;
-                h->as.live.gen = gen;
+        real = real_malloc(asize);
+        if (real) {
+                void *p = hdr2ptr(real);
+                if (!ptr_is_aligned(p, alignment))
+                        p = ptr_align(p, alignment);
+                h = ptr2hdr(p);
+                alloc_insert_rcu(l, h, size, real);
                 *pp = p;
         }
-        else {
-                real = real_malloc(asize);
-                if (real) {
-                        void *p = hdr2ptr(real);
-                        if (!ptr_is_aligned(p, alignment))
-                                p = ptr_align(p, alignment);
-                        h = ptr2hdr(p);
-                        alloc_insert_rcu(l, h, size, real);
-                        *pp = p;
-                }
-                update_stats_rcu_unlock(l);
-        }
+        update_stats_rcu_unlock(l);
 
         return real ? 0 : ENOMEM;
 }
@@ -1243,73 +1077,6 @@ static VALUE total_dec(VALUE mod)
         return SIZET2NUM(total_bytes_dec);
 }
 
-static VALUE hpb_each_yield(VALUE ignore)
-{
-        struct alloc_hdr *h, *next;
-
-        cds_list_for_each_entry_safe(h, next, &hpb_stats.bodies, anode) {
-                VALUE v[2]; /* [ generation, address ] */
-                void *addr = hdr2ptr(h);
-                assert(ptr_is_aligned(addr, HEAP_PAGE_ALIGN));
-                v[0] = LONG2NUM((long)addr);
-                v[1] = SIZET2NUM(h->as.live.gen);
-                rb_yield_values2(2, v);
-        }
-        return Qnil;
-}
-
-/*
- * call-seq:
- *
- *     Mwrap::HeapPageBody.each { |gen, addr| } -> Integer
- *
- * Yields the generation (GC.count) the heap page body was created
- * and address of the heap page body as an Integer.  Returns the
- * number of allocated pages as an Integer.  This return value should
- * match the result of GC.stat(:heap_allocated_pages)
- */
-static VALUE hpb_each(VALUE mod)
-{
-        ++locating;
-        return rb_ensure(hpb_each_yield, Qfalse, reset_locating, 0);
-}
-
-/*
- * call-seq:
- *
- *        Mwrap::HeapPageBody.stat -> Hash
- *        Mwrap::HeapPageBody.stat(hash) -> hash
- *
- * The maximum lifespan of a heap page body in the Ruby VM.
- * This may be Infinity if no heap page bodies were ever freed.
- */
-static VALUE hpb_stat(int argc, VALUE *argv, VALUE hpb)
-{
-        VALUE h;
-
-        rb_scan_args(argc, argv, "01", &h);
-        if (NIL_P(h))
-                h = rb_hash_new();
-        else if (!RB_TYPE_P(h, T_HASH))
-                rb_raise(rb_eTypeError, "not a hash %+"PRIsVALUE, h);
-
-        ++locating;
-#define S(x) ID2SYM(rb_intern(#x))
-        rb_hash_aset(h, S(lifespan_max), acc_max(&hpb_stats.alive));
-        rb_hash_aset(h, S(lifespan_min), acc_min(&hpb_stats.alive));
-        rb_hash_aset(h, S(lifespan_mean), acc_mean(&hpb_stats.alive));
-        rb_hash_aset(h, S(lifespan_stddev), acc_stddev(&hpb_stats.alive));
-        rb_hash_aset(h, S(deathspan_max), acc_max(&hpb_stats.reborn));
-        rb_hash_aset(h, S(deathspan_min), acc_min(&hpb_stats.reborn));
-        rb_hash_aset(h, S(deathspan_mean), acc_mean(&hpb_stats.reborn));
-        rb_hash_aset(h, S(deathspan_stddev), acc_stddev(&hpb_stats.reborn));
-        rb_hash_aset(h, S(resurrects), SIZET2NUM(hpb_stats.reborn.nr));
-#undef S
-        --locating;
-
-        return h;
-}
-
 /*
  * Document-module: Mwrap
  *
@@ -1328,19 +1095,13 @@ static VALUE hpb_stat(int argc, VALUE *argv, VALUE hpb)
  * * dump_fd: a writable FD to dump to
  * * dump_path: a path to dump to, the file is opened in O_APPEND mode
  * * dump_min: the minimum allocation size (total) to dump
- * * dump_heap: mask of heap_page_body statistics to dump
  *
  * If both `dump_fd' and `dump_path' are specified, dump_path takes
  * precedence.
- *
- * dump_heap bitmask
- * * 0x01 - summary stats (same info as HeapPageBody.stat)
- * * 0x02 - all live heaps (similar to HeapPageBody.each)
- * * 0x04 - skip non-heap_page_body-related output
  */
 void Init_mwrap(void)
 {
-        VALUE mod, hpb;
+        VALUE mod;
 
         ++locating;
         mod = rb_define_module("Mwrap");
@@ -1372,67 +1133,9 @@ void Init_mwrap(void)
         rb_define_method(cSrcLoc, "max_lifespan", src_loc_max_lifespan, 0);
         rb_define_method(cSrcLoc, "name", src_loc_name, 0);
 
-        /*
-         * Information about "struct heap_page_body" allocations from
-         * Ruby gc.c.  This can be useful for tracking fragmentation
-         * from posix_memalign(3) use in mainline Ruby:
-         *
-         *   https://sourceware.org/bugzilla/show_bug.cgi?id=14581
-         *
-         * These statistics are never reset by Mwrap.reset or
-         * any other method.  They only make sense in the context
-         * of an entire program lifetime.
-         */
-        hpb = rb_define_class_under(mod, "HeapPageBody", rb_cObject);
-        rb_define_singleton_method(hpb, "stat", hpb_stat, -1);
-        rb_define_singleton_method(hpb, "each", hpb_each, 0);
-
         --locating;
 }
 
-enum {
-        DUMP_HPB_STATS = 0x1,
-        DUMP_HPB_EACH = 0x2,
-        DUMP_HPB_EXCL = 0x4,
-};
-
-static void dump_hpb(FILE *fp, unsigned flags)
-{
-        if (flags & DUMP_HPB_STATS) {
-                fprintf(fp,
-                        "lifespan_max: %"PRId64"\n"
-                        "lifespan_min:%s%"PRId64"\n"
-                        "lifespan_mean: %0.3f\n"
-                        "lifespan_stddev: %0.3f\n"
-                        "deathspan_max: %"PRId64"\n"
-                        "deathspan_min:%s%"PRId64"\n"
-                        "deathspan_mean: %0.3f\n"
-                        "deathspan_stddev: %0.3f\n"
-                        "gc_count: %zu\n",
-                        hpb_stats.alive.max,
-                        hpb_stats.alive.min == INT64_MAX ? " -" : " ",
-                        hpb_stats.alive.min,
-                        hpb_stats.alive.mean,
-                        acc_stddev_dbl(&hpb_stats.alive),
-                        hpb_stats.reborn.max,
-                        hpb_stats.reborn.min == INT64_MAX ? " -" : " ",
-                        hpb_stats.reborn.min,
-                        hpb_stats.reborn.mean,
-                        acc_stddev_dbl(&hpb_stats.reborn),
-                        /* n.b.: unsafe to call rb_gc_count() in destructor */
-                        generation);
-        }
-        if (flags & DUMP_HPB_EACH) {
-                struct alloc_hdr *h;
-
-                cds_list_for_each_entry(h, &hpb_stats.bodies, anode) {
-                        void *addr = hdr2ptr(h);
-
-                        fprintf(fp, "%p\t%zu\n", addr, h->as.live.gen);
-                }
-        }
-}
-
 /* rb_cloexec_open isn't usable by non-Ruby processes */
 #ifndef O_CLOEXEC
 #  define O_CLOEXEC 0
@@ -1446,7 +1149,6 @@ static void mwrap_dump_destructor(void)
         struct dump_arg a = { .min = 0 };
         size_t i;
         int dump_fd;
-        unsigned dump_heap = 0;
         char *dump_path;
         char *s;
 
@@ -1478,9 +1180,6 @@ static void mwrap_dump_destructor(void)
         if ((s = strstr(opt, "dump_min:")))
                 sscanf(s, "dump_min:%zu", &a.min);
 
-        if ((s = strstr(opt, "dump_heap:")))
-                sscanf(s, "dump_heap:%u", &dump_heap);
-
         switch (dump_fd) {
         case 0: goto out;
         case 1: a.fp = stdout; break;
@@ -1500,9 +1199,7 @@ static void mwrap_dump_destructor(void)
                 }
                 /* we'll leak some memory here, but this is a destructor */
         }
-        if ((dump_heap & DUMP_HPB_EXCL) == 0)
-                dump_to_file(&a);
-        dump_hpb(a.fp, dump_heap);
+        dump_to_file(&a);
 out:
         --locating;
 }
diff --git a/lib/mwrap_rack.rb b/lib/mwrap_rack.rb
index 53380b9..c777a78 100644
--- a/lib/mwrap_rack.rb
+++ b/lib/mwrap_rack.rb
@@ -89,54 +89,6 @@ class MwrapRack
     end
   end
 
-  class HeapPages # :nodoc:
-    include HtmlResponse
-    HEADER = '<tr><th>address</th><th>generation</th></tr>'
-
-    def hpb_rows
-      Mwrap::HeapPageBody.stat(stat = Thread.current[:mwrap_hpb_stat] ||= {})
-      %i(lifespan_max lifespan_min lifespan_mean lifespan_stddev
-         deathspan_max deathspan_min deathspan_mean deathspan_stddev
-         resurrects
-        ).map! do |k|
-         "<tr><td>#{k}</td><td>#{stat[k]}</td></tr>\n"
-      end.join
-    end
-
-    def gc_stat_rows
-      GC.stat(stat = Thread.current[:mwrap_gc_stat] ||= {})
-      %i(count heap_allocated_pages heap_eden_pages heap_tomb_pages
-          total_allocated_pages total_freed_pages).map do |k|
-         "<tr><td>GC.stat(:#{k})</td><td>#{stat[k]}</td></tr>\n"
-      end.join
-    end
-
-    GC_STAT_URL = 'https://docs.ruby-lang.org/en/trunk/GC.html#method-c-stat'
-    GC_STAT_HELP = <<~EOM
-      <p>Non-Infinity lifespans can indicate fragmentation.
-      <p>See <a
-      href="#{GC_STAT_URL}">#{GC_STAT_URL}</a> for info on GC.stat values.
-    EOM
-
-    def each
-      Mwrap.quiet do
-        yield("<html><head><title>heap pages</title></head>" \
-              "<body><h1>heap pages</h1>" \
-              "<table><tr><th>stat</th><th>value</th></tr>\n" \
-              "#{hpb_rows}" \
-              "#{gc_stat_rows}" \
-              "</table>\n" \
-              "#{GC_STAT_HELP}" \
-              "<table>#{HEADER}")
-        Mwrap::HeapPageBody.each do |addr, generation|
-          addr = -sprintf('0x%x', addr)
-          yield(-"<tr><td>#{addr}</td><td>#{generation}</td></tr>\n")
-        end
-        yield "</table></body></html>\n"
-      end
-    end
-  end
-
   def r404 # :nodoc:
     [404,{'Content-Type'=>'text/plain'},["Not found\n"]]
   end
@@ -152,15 +104,12 @@ class MwrapRack
       loc = -CGI.unescape($1)
       loc = Mwrap[loc] or return r404
       EachAt.new(loc).response
-    when '/heap_pages'
-      HeapPages.new.response
     when '/'
       n = 2000
       u = 'https://80x24.org/mwrap/README.html'
       b = -('<html><head><title>Mwrap demo</title></head>' \
           "<body><p><a href=\"each/#{n}\">allocations &gt;#{n} bytes</a>" \
           "<p><a href=\"#{u}\">#{u}</a>" \
-          "<p><a href=\"heap_pages\">heap pages</a>" \
           "</body></html>\n")
       [ 200, {'Content-Type'=>'text/html','Content-Length'=>-b.size.to_s},[b]]
     else
diff --git a/test/test_mwrap.rb b/test/test_mwrap.rb
index eaa65cb..6522167 100644
--- a/test/test_mwrap.rb
+++ b/test/test_mwrap.rb
@@ -59,13 +59,6 @@ class TestMwrap < Test::Unit::TestCase
       res = system(env, *cmd)
       assert res, $?.inspect
       assert_match(/\b1\d{4}\s+[1-9]\d*\s+-e:1$/, tmp.read)
-
-      tmp.rewind
-      tmp.truncate(0)
-      env['MWRAP'] = "dump_path:#{tmp.path},dump_heap:5"
-      res = system(env, *cmd)
-      assert res, $?.inspect
-      assert_match %r{lifespan_stddev}, tmp.read
     end
   end
 
@@ -295,35 +288,4 @@ class TestMwrap < Test::Unit::TestCase
         abort 'freed more than allocated'
     end;
   end
-
-  def test_heap_page_body
-    assert_separately(+"#{<<~"begin;"}\n#{<<~'end;'}")
-    begin;
-      require 'mwrap'
-      require 'rubygems' # use up some memory
-      ap = GC.stat(:heap_allocated_pages)
-      h = {}
-      nr = 0
-      Mwrap::HeapPageBody.each do |addr, gen|
-        nr += 1
-        gen <= GC.count && gen >= 0 or abort "bad generation: #{gen}"
-        (0 == (addr & 16383)) or abort "addr not aligned: #{'%x' % addr}"
-      end
-      if RUBY_VERSION.to_f < 3.1 # 3.1+ uses mmap on platforms we care about
-        nr == ap or abort "HeapPageBody.each missed page #{nr} != #{ap}"
-      end
-      10.times { (1..20000).to_a.map(&:to_s) }
-      3.times { GC.start }
-      Mwrap::HeapPageBody.stat(h)
-      Integer === h[:lifespan_max] or abort 'lifespan_max not recorded'
-      Integer === h[:lifespan_min] or abort 'lifespan_min not recorded'
-      Float === h[:lifespan_mean] or abort 'lifespan_mean not recorded'
-      3.times { GC.start }
-      10.times { (1..20000).to_a.map(&:to_s) }
-      Mwrap::HeapPageBody.stat(h)
-      h[:deathspan_min] <= h[:deathspan_max] or
-        abort 'wrong min/max deathtime'
-      Float === h[:deathspan_mean] or abort 'deathspan_mean not recorded'
-    end;
-  end
 end