diff options
| -rw-r--r-- | src/common/buffer.cc | 66 | ||||
| -rw-r--r-- | src/test/bufferlist.cc | 17 |
2 files changed, 58 insertions, 25 deletions
diff --git a/src/common/buffer.cc b/src/common/buffer.cc index 29d78f37e74..7d80a4587fb 100644 --- a/src/common/buffer.cc +++ b/src/common/buffer.cc @@ -31,6 +31,9 @@ namespace ceph { + +static unsigned char zbuf[128]; + #ifdef BUFFER_DEBUG static uint32_t simple_spinlock_t buffer_debug_lock = SIMPLE_SPINLOCK_INITIALIZER; # define bdout { simple_spin_lock(&buffer_debug_lock); std::cout @@ -62,6 +65,7 @@ bool buffer_track_alloc = get_env_bool("CEPH_BUFFER_TRACK"); atomic_t nref; Spinlock crc_lock; + map<pair<off_t, off_t>, pair<int64_t, int64_t> > crc_map; int64_t crc_in; ///< cached crc base; -1 if invalid int64_t crc_out; ///< cached crc value; -1 if invalid @@ -92,24 +96,20 @@ bool buffer_track_alloc = get_env_bool("CEPH_BUFFER_TRACK"); bool is_n_page_sized() { return (len & ~CEPH_PAGE_MASK) == 0; } - bool have_crc() const { + bool get_crc(const pair<off_t, off_t> &fromto, + pair<int64_t, int64_t> *crc) const { Spinlock::Locker l(crc_lock); - return crc_in >= 0; - } - uint32_t get_crc_base() const { - Spinlock::Locker l(crc_lock); - assert(crc_in >= 0); - return crc_in; - } - uint32_t get_crc_value() const { - Spinlock::Locker l(crc_lock); - assert(crc_out >= 0); - return crc_out; + map<pair<off_t, off_t>, pair<int64_t, int64_t> >::const_iterator i = + crc_map.find(fromto); + if (i == crc_map.end()) + return false; + *crc = i->second; + return true; } - void set_crc(uint32_t b, uint32_t v) { + void set_crc(const pair<off_t, off_t> &fromto, + const pair<uint64_t, uint64_t> &crc) { Spinlock::Locker l(crc_lock); - crc_in = b; - crc_out = v; + crc_map[fromto] = crc; } }; @@ -1299,24 +1299,40 @@ __u32 buffer::list::crc32c(__u32 crc) const { for (std::list<ptr>::const_iterator it = _buffers.begin(); it != _buffers.end(); - ++it) + ++it) { if (it->length()) { raw *r = it->get_raw(); - if (it->offset() == 0 && - it->length() == r->length()) { - if (r->have_crc() && - r->get_crc_base() == crc) { - crc = r->get_crc_value(); + pair<off_t, off_t> ofs(it->offset(), it->offset() + it->length()); + pair<int64_t, int64_t> ccrc; + if (r->get_crc(ofs, &ccrc)) { + if (ccrc.first == crc) { + // got it already + crc = ccrc.second; } else { - uint32_t base = crc; - crc = ceph_crc32c(crc, (unsigned char*)it->c_str(), it->length()); - r->set_crc(base, crc); + /* If we have cached crc32c(buf, v) for initial value v, + * we can convert this to a different initial value v' by: + * crc32c(buf, v') = crc32c(buf, v) ^ adjustment + * where adjustment = crc32c(0*len(buf), v ^ v') + * + * http://crcutil.googlecode.com/files/crc-doc.1.0.pdf + * note, u for our crc32c implementation is 0 + */ + int64_t adjustment = ccrc.first ^ crc; + size_t remaining = it->length(); + for (; remaining > sizeof(zbuf); remaining -= sizeof(zbuf)) { + adjustment = ceph_crc32c(adjustment, zbuf, sizeof(zbuf)); + } + if (remaining) + adjustment = ceph_crc32c(adjustment, zbuf, remaining); + crc = ccrc.second ^ adjustment; } } else { - // partial extent of raw buffer; continue + uint32_t base = crc; crc = ceph_crc32c(crc, (unsigned char*)it->c_str(), it->length()); + r->set_crc(ofs, make_pair(base, crc)); } } + } return crc; } diff --git a/src/test/bufferlist.cc b/src/test/bufferlist.cc index b23bd33e55a..beae868c0da 100644 --- a/src/test/bufferlist.cc +++ b/src/test/bufferlist.cc @@ -1649,6 +1649,23 @@ TEST(BufferList, crc32c) { EXPECT_EQ((unsigned)0x5FA5C0CC, crc); } +TEST(BufferList, crc32cappend) { + bufferlist bl1; + bufferlist bl2; + + for (int j = 0; j < 200; ++j) { + bufferlist bl; + for (int i = 0; i < 200; ++i) { + char x = rand(); + bl.append(x); + bl1.append(x); + } + bl.crc32c(rand()); // mess with the cached bufferptr crc values + bl2.append(bl); + } + ASSERT_EQ(bl1.crc32c(0), bl2.crc32c(0)); +} + TEST(BufferList, compare) { bufferlist a; a.append("A"); |