gitify the tree, especially the web makefile.

[ccan] / ccan / tdb2 / free.c

diff --git a/ccan/tdb2/free.c b/ccan/tdb2/free.c
index efc29e884ea2078c54ed28616b9d0cdce1228ac1..e6d871a58607180c9a81afec54ccbdc7a88c0e2a 100644 (file)
--- a/ccan/tdb2/free.c
+++ b/ccan/tdb2/free.c
@@ -17,54 +17,14 @@
 */
 #include "private.h"
 #include <ccan/likely/likely.h>
+#include <ccan/ilog/ilog.h>
 #include <time.h>
 #include <assert.h>
 #include <limits.h>
 
-/* We have to be able to fit a free record here. */
-#define MIN_DATA_LEN   \
-       (sizeof(struct tdb_free_record) - sizeof(struct tdb_used_record))
-
 static unsigned fls64(uint64_t val)
 {
-#if HAVE_BUILTIN_CLZL
-       if (val <= ULONG_MAX) {
-               /* This is significantly faster! */
-               return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
-       } else {
-#endif
-       uint64_t r = 64;
-
-       if (!val)
-               return 0;
-       if (!(val & 0xffffffff00000000ull)) {
-               val <<= 32;
-               r -= 32;
-       }
-       if (!(val & 0xffff000000000000ull)) {
-               val <<= 16;
-               r -= 16;
-       }
-       if (!(val & 0xff00000000000000ull)) {
-               val <<= 8;
-               r -= 8;
-       }
-       if (!(val & 0xf000000000000000ull)) {
-               val <<= 4;
-               r -= 4;
-       }
-       if (!(val & 0xc000000000000000ull)) {
-               val <<= 2;
-               r -= 2;
-       }
-       if (!(val & 0x8000000000000000ull)) {
-               val <<= 1;
-               r -= 1;
-       }
-       return r;
-#if HAVE_BUILTIN_CLZL
-       }
-#endif
+       return ilog64(val);
 }
 
 /* In which bucket would we find a particular record size? (ignoring header) */
@@ -73,15 +33,15 @@ unsigned int size_to_bucket(unsigned int zone_bits, tdb_len_t data_len)
        unsigned int bucket;
 
        /* We can't have records smaller than this. */
-       assert(data_len >= MIN_DATA_LEN);
+       assert(data_len >= TDB_MIN_DATA_LEN);
 
        /* Ignoring the header... */
-       if (data_len - MIN_DATA_LEN <= 64) {
-               /* 0 in bucket 0, 8 in bucket 1... 64 in bucket 6. */
-               bucket = (data_len - MIN_DATA_LEN) / 8;
+       if (data_len - TDB_MIN_DATA_LEN <= 64) {
+               /* 0 in bucket 0, 8 in bucket 1... 64 in bucket 8. */
+               bucket = (data_len - TDB_MIN_DATA_LEN) / 8;
        } else {
                /* After that we go power of 2. */
-               bucket = fls64(data_len - MIN_DATA_LEN) + 2;
+               bucket = fls64(data_len - TDB_MIN_DATA_LEN) + 2;
        }
 
        if (unlikely(bucket > BUCKETS_FOR_ZONE(zone_bits)))
@@ -164,13 +124,10 @@ tdb_off_t bucket_off(tdb_off_t zone_off, tdb_off_t bucket)
 /* Returns free_buckets + 1, or list number to search. */
 static tdb_off_t find_free_head(struct tdb_context *tdb, tdb_off_t bucket)
 {
-       tdb_off_t b;
-
        /* Speculatively search for a non-zero bucket. */
-       b = tdb_find_nonzero_off(tdb, bucket_off(tdb->zone_off, bucket),
-                                BUCKETS_FOR_ZONE(tdb->zhdr.zone_bits) + 1
-                                - bucket);
-       return bucket + b;
+       return tdb_find_nonzero_off(tdb, bucket_off(tdb->zone_off, 0),
+                                   bucket,
+                                   BUCKETS_FOR_ZONE(tdb->zhdr.zone_bits) + 1);
 }
 
 /* Remove from free bucket. */
@@ -372,6 +329,9 @@ static tdb_off_t lock_and_alloc(struct tdb_context *tdb,
 again:
        b_off = bucket_off(zone_off, bucket);
 
+       /* FIXME: Try non-blocking wait first, to measure contention.
+        * If we're contented, try switching zones, and don't enlarge zone
+        * next time (we want more zones). */
        /* Lock this bucket. */
        if (tdb_lock_free_bucket(tdb, b_off, TDB_LOCK_WAIT) == -1) {
                return TDB_OFF_ERR;
@@ -466,6 +426,10 @@ static tdb_off_t get_free(struct tdb_context *tdb, size_t size,
        tdb_off_t start_zone = tdb->zone_off, off;
        bool wrapped = false;
 
+       /* FIXME: If we don't get a hit in the first bucket we want,
+        * try changing zones for next time.  That should help wear
+        * zones evenly, so we don't need to search all of them before
+        * expanding. */
        while (!wrapped || tdb->zone_off != start_zone) {
                tdb_off_t b;
 
@@ -510,10 +474,10 @@ int set_header(struct tdb_context *tdb,
 {
        uint64_t keybits = (fls64(keylen) + 1) / 2;
 
-       /* Use top bits of hash, so it's independent of hash table size. */
+       /* Use bottom bits of hash, so it's independent of hash table size. */
        rec->magic_and_meta
                = zone_bits
-               | ((hash >> 59) << 6)
+               | ((hash & ((1 << 5)-1)) << 6)
                | ((actuallen - (keylen + datalen)) << 11)
                | (keybits << 43)
                | (TDB_MAGIC << 48);
@@ -570,6 +534,7 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
        if (tdb->map_size != old_size)
                goto success;
 
+       /* FIXME: Tailer is a bogus optimization, remove it. */
        /* zone bits tailer char is protected by EXPAND lock. */
        if (tdb->methods->read(tdb, old_size - 1, &zone_bits, 1) == -1)
                goto fail;
@@ -596,6 +561,7 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
        zhdr.zone_bits = zone_bits;
        num_buckets = BUCKETS_FOR_ZONE(zone_bits);
 
+       /* FIXME: I don't think we need to expand to full zone, do we? */
        if (tdb->methods->expand_file(tdb, 1ULL << zone_bits) == -1)
                goto fail;
 
@@ -635,8 +601,8 @@ static tdb_len_t adjust_size(size_t keylen, size_t datalen, bool growing)
 {
        tdb_len_t size = keylen + datalen;
 
-       if (size < MIN_DATA_LEN)
-               size = MIN_DATA_LEN;
+       if (size < TDB_MIN_DATA_LEN)
+               size = TDB_MIN_DATA_LEN;
 
        /* Overallocate if this is coming from an enlarging store. */
        if (growing)
@@ -654,8 +620,8 @@ tdb_off_t alloc(struct tdb_context *tdb, size_t keylen, size_t datalen,
        tdb_len_t size, actual;
        struct tdb_used_record rec;
 
-       /* We don't want header to change during this! */
-       assert(tdb->header_uptodate);
+       /* We can't hold pointers during this: we could unmap! */
+       assert(!tdb->direct_access);
 
        size = adjust_size(keylen, datalen, growing);