Changeset 3138 for vendor/gnumake/current/strcache.c

Timestamp:

Mar 12, 2018, 8:32:29 PM (7 years ago)

Author:

bird

Message:

Imported make 4.2.1 (2e55f5e4abdc0e38c1d64be703b446695e70b3b6) from ​https://git.savannah.gnu.org/git/make.git.

File:

• vendor/gnumake/current/strcache.c (modified) (9 diffs)

vendor/gnumake/current/strcache.c

@@ -1 +1 @@
 /* Constant string caching for GNU Make.
-Copyright (C) 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+Copyright (C) 2006-2016 Free Software Foundation, Inc.
 This file is part of GNU Make.
 
@@ -15 +15 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#include "make.h"
-
+#include "makeint.h"
+
+#include <stddef.h>
 #include <assert.h>
 
 #include "hash.h"
-
-/* The size (in bytes) of each cache buffer.
-   Try to pick something that will map well into the heap.  */
-#define CACHE_BUFFER_SIZE   (8192 - 16)
-
 
 /* A string cached here will never be freed, so we don't need to worry about
@@ -30 +26 @@
    hash so it can be looked up again. */
 
+typedef unsigned short int sc_buflen_t;
+
 struct strcache {
-  struct strcache *next;    /* The next block of strings.  */
-  char *end;                /* Pointer to the beginning of the free space.  */
-  int count;                /* # of strings in this buffer (for stats).  */
-  int bytesfree;            /* The amount of the buffer that is free.  */
+  struct strcache *next;    /* The next block of strings.  Must be first!  */
+  sc_buflen_t end;          /* Offset to the beginning of free space.  */
+  sc_buflen_t bytesfree;    /* Free space left in this buffer.  */
+  sc_buflen_t count;        /* # of strings in this buffer (for stats).  */
   char buffer[1];           /* The buffer comes after this.  */
 };
 
-static int bufsize = CACHE_BUFFER_SIZE;
+/* The size (in bytes) of each cache buffer.
+   Try to pick something that will map well into the heap.
+   This must be able to be represented by a short int (<=65535).  */
+#define CACHE_BUFFER_BASE       (8192)
+#define CACHE_BUFFER_ALLOC(_s)  ((_s) - (2 * sizeof (size_t)))
+#define CACHE_BUFFER_OFFSET     (offsetof (struct strcache, buffer))
+#define CACHE_BUFFER_SIZE(_s)   (CACHE_BUFFER_ALLOC(_s) - CACHE_BUFFER_OFFSET)
+#define BUFSIZE                 CACHE_BUFFER_SIZE (CACHE_BUFFER_BASE)
+
 static struct strcache *strcache = NULL;
+static struct strcache *fullcache = NULL;
+
+static unsigned long total_buffers = 0;
+static unsigned long total_strings = 0;
+static unsigned long total_size = 0;
 
 /* Add a new buffer to the cache.  Add it at the front to reduce search time.
@@ -47 +58 @@
  */
 static struct strcache *
-new_cache()
-{
-  struct strcache *new;
-  new = xmalloc (sizeof (*new) + bufsize);
-  new->end = new->buffer;
+new_cache (struct strcache **head, sc_buflen_t buflen)
+{
+  struct strcache *new = xmalloc (buflen + CACHE_BUFFER_OFFSET);
+  new->end = 0;
   new->count = 0;
-  new->bytesfree = bufsize;
-
-  new->next = strcache;
-  strcache = new;
-
+  new->bytesfree = buflen;
+
+  new->next = *head;
+  *head = new;
+
+  ++total_buffers;
   return new;
 }
 
 static const char *
-add_string(const char *str, int len)
-{
-  struct strcache *best = NULL;
+copy_string (struct strcache *sp, const char *str, unsigned int len)
+{
+  /* Add the string to this cache.  */
+  char *res = &sp->buffer[sp->end];
+
+  memmove (res, str, len);
+  res[len++] = '\0';
+  sp->end += len;
+  sp->bytesfree -= len;
+  ++sp->count;
+
+  return res;
+}
+
+static const char *
+add_string (const char *str, unsigned int len)
+{
+  const char *res;
   struct strcache *sp;
-  const char *res;
+  struct strcache **spp = &strcache;
+  /* We need space for the nul char.  */
+  unsigned int sz = len + 1;
+
+  ++total_strings;
+  total_size += sz;
 
   /* If the string we want is too large to fit into a single buffer, then
-     we're screwed; nothing will ever fit!  Change the maximum size of the
-     cache to be big enough.  */
-  if (len > bufsize)
-    bufsize = len * 2;
-
-  /* First, find a cache with enough free space.  We always look through all
-     the blocks and choose the one with the best fit (the one that leaves the
-     least amount of space free).  */
-  for (sp = strcache; sp != NULL; sp = sp->next)
-    if (sp->bytesfree > len && (!best || best->bytesfree > sp->bytesfree))
-      best = sp;
-
-  /* If nothing is big enough, make a new cache.  */
-  if (!best)
-    best = new_cache();
-
-  assert (best->bytesfree > len);
-
-  /* Add the string to the best cache.  */
-  res = best->end;
-  memcpy (best->end, str, len);
-  best->end += len;
-  *(best->end++) = '\0';
-  best->bytesfree -= len + 1;
-  ++best->count;
+     no existing cache is large enough.  Add it directly to the fullcache.  */
+  if (sz > BUFSIZE)
+    {
+      sp = new_cache (&fullcache, sz);
+      return copy_string (sp, str, len);
+    }
+
+  /* Find the first cache with enough free space.  */
+  for (; *spp != NULL; spp = &(*spp)->next)
+    if ((*spp)->bytesfree > sz)
+      break;
+  sp = *spp;
+
+  /* If nothing is big enough, make a new cache at the front.  */
+  if (sp == NULL)
+    {
+      sp = new_cache (&strcache, BUFSIZE);
+      spp = &strcache;
+    }
+
+  /* Add the string to this cache.  */
+  res = copy_string (sp, str, len);
+
+  /* If the amount free in this cache is less than the average string size,
+     consider it full and move it to the full list.  */
+  if (total_strings > 20 && sp->bytesfree < (total_size / total_strings) + 1)
+    {
+      *spp = sp->next;
+      sp->next = fullcache;
+      fullcache = sp;
+    }
 
   return res;
 }
 
+/* For strings too large for the strcache, we just save them in a list.  */
+struct hugestring {
+  struct hugestring *next;  /* The next string.  */
+  char buffer[1];           /* The string.  */
+};
+
+static struct hugestring *hugestrings = NULL;
+
+static const char *
+add_hugestring (const char *str, unsigned int len)
+{
+  struct hugestring *new = xmalloc (sizeof (struct hugestring) + len);
+  memcpy (new->buffer, str, len);
+  new->buffer[len] = '\0';
+
+  new->next = hugestrings;
+  hugestrings = new;
+
+  return new->buffer;
+}
 
 /* Hash table of strings in the cache.  */
@@ -123 +180 @@
 
 static const char *
-add_hash (const char *str, int len)
-{
+add_hash (const char *str, unsigned int len)
+{
+  char *const *slot;
+  const char *key;
+
+  /* If it's too large for the string cache, just copy it.
+     We don't bother trying to match these.  */
+  if (len > USHRT_MAX - 1)
+    return add_hugestring (str, len);
+
   /* Look up the string in the hash.  If it's there, return it.  */
-  char *const *slot = (char *const *) hash_find_slot (&strings, str);
-  const char *key = *slot;
-
-  /* Count the total number of adds we performed.  */
+  slot = (char *const *) hash_find_slot (&strings, str);
+  key = *slot;
+
+  /* Count the total number of add operations we performed.  */
   ++total_adds;
 
@@ -148 +213 @@
 
   for (sp = strcache; sp != 0; sp = sp->next)
-    if (str >= sp->buffer && str < sp->end)
+    if (str >= sp->buffer && str < sp->buffer + sp->end)
       return 1;
+  for (sp = fullcache; sp != 0; sp = sp->next)
+    if (str >= sp->buffer && str < sp->buffer + sp->end)
+      return 1;
+
+  {
+    struct hugestring *hp;
+    for (hp = hugestrings; hp != 0; hp = hp->next)
+      if (str == hp->buffer)
+        return 1;
+  }
 
   return 0;
@@ -164 +239 @@
 
 const char *
-strcache_add_len (const char *str, int len)
+strcache_add_len (const char *str, unsigned int len)
 {
   /* If we're not given a nul-terminated string we have to create one, because
@@ -179 +254 @@
 }
 
-int
-strcache_setbufsize(int size)
-{
-  if (size > bufsize)
-    bufsize = size;
-  return bufsize;
-}
-
 void
 strcache_init (void)
@@ -199 +266 @@
 strcache_print_stats (const char *prefix)
 {
-  int numbuffs = 0, numstrs = 0;
-  int totsize = 0, avgsize, maxsize = 0, minsize = bufsize;
-  int totfree = 0, avgfree, maxfree = 0, minfree = bufsize;
-  int lastused = 0, lastfree = 0;
-
-  if (strcache)
-    {
-      const struct strcache *sp;
-
-      /* Count the first buffer separately since it's not full.  */
-      lastused = strcache->end - strcache->buffer;
-      lastfree = strcache->bytesfree;
-
-      for (sp = strcache->next; sp != NULL; sp = sp->next)
-        {
-          int bf = sp->bytesfree;
-          int sz = sp->end - sp->buffer;
-
-          ++numbuffs;
-          numstrs += sp->count;
-
-          totsize += sz;
-          maxsize = (sz > maxsize ? sz : maxsize);
-          minsize = (sz < minsize ? sz : minsize);
-
-          totfree += bf;
-          maxfree = (bf > maxfree ? bf : maxfree);
-          minfree = (bf < minfree ? bf : minfree);
-        }
-    }
-
-  avgsize = numbuffs ? (int)(totsize / numbuffs) : 0;
-  avgfree = numbuffs ? (int)(totfree / numbuffs) : 0;
-
-  printf (_("\n%s # of strings in strcache: %d / lookups = %lu / hits = %lu\n"),
-          prefix, numstrs, total_adds, (total_adds - numstrs));
-  printf (_("%s # of strcache buffers: %d (* %d B/buffer = %d B)\n"),
-          prefix, (numbuffs + 1), bufsize, ((numbuffs + 1) * bufsize));
-  printf (_("%s strcache used: total = %d (%d) / max = %d / min = %d / avg = %d\n"),
-          prefix, totsize, lastused, maxsize, minsize, avgsize);
-  printf (_("%s strcache free: total = %d (%d) / max = %d / min = %d / avg = %d\n"),
-          prefix, totfree, lastfree, maxfree, minfree, avgfree);
-
-  fputs (_("\n# strcache hash-table stats:\n# "), stdout);
+  const struct strcache *sp;
+  unsigned long numbuffs = 0, fullbuffs = 0;
+  unsigned long totfree = 0, maxfree = 0, minfree = BUFSIZE;
+
+  if (! strcache)
+    {
+      printf (_("\n%s No strcache buffers\n"), prefix);
+      return;
+    }
+
+  /* Count the first buffer separately since it's not full.  */
+  for (sp = strcache->next; sp != NULL; sp = sp->next)
+    {
+      sc_buflen_t bf = sp->bytesfree;
+
+      totfree += bf;
+      maxfree = (bf > maxfree ? bf : maxfree);
+      minfree = (bf < minfree ? bf : minfree);
+
+      ++numbuffs;
+    }
+  for (sp = fullcache; sp != NULL; sp = sp->next)
+    {
+      sc_buflen_t bf = sp->bytesfree;
+
+      totfree += bf;
+      maxfree = (bf > maxfree ? bf : maxfree);
+      minfree = (bf < minfree ? bf : minfree);
+
+      ++numbuffs;
+      ++fullbuffs;
+    }
+
+  /* Make sure we didn't lose any buffers.  */
+  assert (total_buffers == numbuffs + 1);
+
+  printf (_("\n%s strcache buffers: %lu (%lu) / strings = %lu / storage = %lu B / avg = %lu B\n"),
+          prefix, numbuffs + 1, fullbuffs, total_strings, total_size,
+          (total_size / total_strings));
+
+  printf (_("%s current buf: size = %hu B / used = %hu B / count = %hu / avg = %hu B\n"),
+          prefix, (sc_buflen_t)BUFSIZE, strcache->end, strcache->count,
+          (strcache->end / strcache->count));
+
+  if (numbuffs)
+    {
+      /* Show information about non-current buffers.  */
+      unsigned long sz = total_size - strcache->end;
+      unsigned long cnt = total_strings - strcache->count;
+      sc_buflen_t avgfree = totfree / numbuffs;
+
+      printf (_("%s other used: total = %lu B / count = %lu / avg = %lu B\n"),
+              prefix, sz, cnt, sz / cnt);
+
+      printf (_("%s other free: total = %lu B / max = %lu B / min = %lu B / avg = %hu B\n"),
+              prefix, totfree, maxfree, minfree, avgfree);
+    }
+
+  printf (_("\n%s strcache performance: lookups = %lu / hit rate = %lu%%\n"),
+          prefix, total_adds, (long unsigned)(100.0 * (total_adds - total_strings) / total_adds));
+  fputs (_("# hash-table stats:\n# "), stdout);
   hash_print_stats (&strings, stdout);
 }