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Extend layer limit from 255 to 65535 by using 16-bit tag field #385

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Extend layer limit from 255 to 65535 by using 16-bit tag field #385

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2 changes: 1 addition & 1 deletion src/config.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@
#include "overlaybd/config_util.h"

namespace ImageConfigNS {
const int MAX_LAYER_CNT = 256;
const int MAX_LAYER_CNT = 65536;

struct LayerConfig : public ConfigUtils::Config {
APPCFG_CLASS;
Expand Down
20 changes: 10 additions & 10 deletions src/overlaybd/lsmt/file.cpp
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Expand Up @@ -692,7 +692,7 @@ class LSMTFile : public LSMTReadOnlyFile {
bool m_init_concurrency = false;
uint64_t m_data_offset = HeaderTrailer::SPACE / ALIGNMENT;

uint8_t m_rw_tag = 0;
uint16_t m_rw_tag = 0;

Mutex m_rw_mtx;
IFile *m_findex = nullptr;
Expand Down Expand Up @@ -1120,7 +1120,7 @@ class LSMTWarpFile : public LSMTFile {

virtual ssize_t pwrite(const void *buf, size_t count, off_t offset) override {
LOG_DEBUG("write fs meta {offset: `, len: `}", offset, count);
auto tag = m_rw_tag + (uint8_t)SegmentType::fsMeta;
auto tag = m_rw_tag + (uint16_t)SegmentType::fsMeta;
SegmentMapping m{
(uint64_t)offset / (uint64_t)ALIGNMENT,
(uint32_t)count / (uint32_t)ALIGNMENT,
Expand Down Expand Up @@ -1159,7 +1159,7 @@ class LSMTWarpFile : public LSMTFile {
m.length = (Segment::MAX_LENGTH < lba.count / ALIGNMENT ? Segment::MAX_LENGTH
: lba.count / ALIGNMENT);
m.moffset = lba.roffset / ALIGNMENT;
m.tag = m_rw_tag + (uint8_t)SegmentType::remoteData;
m.tag = m_rw_tag + (uint16_t)SegmentType::remoteData;
LOG_DEBUG("insert segment: ` into findex: `", m, m_findex);
static_cast<IMemoryIndex0 *>(m_index)->insert(m);
append_index(m);
Expand All @@ -1179,7 +1179,7 @@ class LSMTWarpFile : public LSMTFile {
size_t compacted_idx_size = 0;
moffset /= ALIGNMENT;
for (auto &m : marray) {
if (m.tag == (uint8_t)SegmentType::remoteData) {
if (m.tag == (uint16_t)SegmentType::remoteData) {
compact_index.push_back(m);
compacted_idx_size++;
continue;
Expand Down Expand Up @@ -1271,7 +1271,7 @@ static HeaderTrailer *verify_ht(IFile *file, char *buf, bool is_trailer, ssize_t
}

static SegmentMapping *do_load_index(IFile *file, HeaderTrailer *pheader_trailer, bool trailer,
uint8_t warp_file_tag = 0) {
uint16_t warp_file_tag = 0) {

ALIGNED_MEM(buf, HeaderTrailer::SPACE, ALIGNMENT4K);
auto pht = verify_ht(file, buf);
Expand Down Expand Up @@ -1315,7 +1315,7 @@ static SegmentMapping *do_load_index(IFile *file, HeaderTrailer *pheader_trailer
}

size_t index_size = 0;
uint8_t min_tag = 255;
uint16_t min_tag = 65535;
for (size_t i = 0; i < pht->index_size; ++i) {
if (ibuf[i].offset != SegmentMapping::INVALID_OFFSET) {
ibuf[index_size] = ibuf[i];
Expand All @@ -1329,9 +1329,9 @@ static SegmentMapping *do_load_index(IFile *file, HeaderTrailer *pheader_trailer
LOG_INFO("rebuild index tag for LSMTWarpFile.");
for (size_t i = 0; i < index_size; i++) {
if (warp_file_tag == 1) /* only fsmeta */
ibuf[i].tag = (uint8_t)SegmentType::fsMeta;
ibuf[i].tag = (uint16_t)SegmentType::fsMeta;
if (warp_file_tag == 2) /* only remote data */
ibuf[i].tag = (uint8_t)SegmentType::remoteData;
ibuf[i].tag = (uint16_t)SegmentType::remoteData;
if (warp_file_tag == 3) /* only remote data */
ibuf[i].tag -= min_tag;
LOG_DEBUG("`", ibuf[i]);
Expand Down Expand Up @@ -1485,8 +1485,8 @@ IFileRW *create_warpfile(WarpFileArgs &args, bool ownership) {
write_header_trailer(rst->m_findex, true, false, false, HeaderTrailer::SPACE, 0, info);
rst->m_index = create_memory_index0((const SegmentMapping *)nullptr, 0, 0, 0);
rst->m_files.resize(2);
rst->m_files[(uint8_t)SegmentType::fsMeta] = args.fsmeta;
rst->m_files[(uint8_t)SegmentType::remoteData] = args.target_file;
rst->m_files[(uint16_t)SegmentType::fsMeta] = args.fsmeta;
rst->m_files[(uint16_t)SegmentType::remoteData] = args.target_file;
rst->m_vsize = args.virtual_size;
rst->m_file_ownership = ownership;
UUID raw;
Expand Down
2 changes: 1 addition & 1 deletion src/overlaybd/lsmt/file.h
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Expand Up @@ -33,7 +33,7 @@ IMemoryIndex -> IMemoryIndex0 -> IComboIndex -> Index0 ( set<SegmentMap> ) -> Co

namespace LSMT {

static const int MAX_STACK_LAYERS = 255;
static const int MAX_STACK_LAYERS = 65535;

static const uint32_t ALIGNMENT = 512; // same as trim block size.
static const uint32_t ALIGNMENT4K = 4096;
Expand Down
8 changes: 4 additions & 4 deletions src/overlaybd/lsmt/index.cpp
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Expand Up @@ -629,7 +629,7 @@ class ComboIndex : public Index0 {
Index *m_backing_index{nullptr};
bool m_ownership;

ComboIndex(Index0 *index0, const Index *index, uint8_t ro_layers_count, bool ownership) {
ComboIndex(Index0 *index0, const Index *index, uint16_t ro_layers_count, bool ownership) {
m_index0 = index0;
m_backing_index = const_cast<Index *>(index);
mapping = index0->mapping;
Expand Down Expand Up @@ -853,7 +853,7 @@ static void merge_indexes(uint8_t level, vector<SegmentMapping> &mapping, const
}

IComboIndex *create_combo_index(IMemoryIndex0 *index0, const IMemoryIndex *index,
uint8_t ro_index_count, bool ownership) {
uint16_t ro_index_count, bool ownership) {
if (!index0 || !index)
LOG_ERROR_RETURN(EINVAL, nullptr, "invalid argument(s)");

Expand Down Expand Up @@ -903,8 +903,8 @@ size_t compress_raw_index_predict(const SegmentMapping *mapping, size_t n) {
}

IMemoryIndex *merge_memory_indexes(const IMemoryIndex **pindexes, size_t n) {
if (n > 255) {
LOG_ERROR("too many indexes to merge, 255 at most!");
if (n > 65535) {
LOG_ERROR("too many indexes to merge, 65535 at most!");
return nullptr;
}
if (n == 0 || pindexes == nullptr)
Expand Down
12 changes: 6 additions & 6 deletions src/overlaybd/lsmt/index.h
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Expand Up @@ -51,15 +51,15 @@ struct Segment {
}
} __attribute__((packed));

struct SegmentMapping : public Segment { // 64 + 55 + 9 == 128
uint64_t moffset : 55; // mapped offset (2^64 B if in sector)
struct SegmentMapping : public Segment { // 64 + 47 + 1 + 16 == 128
uint64_t moffset : 47; // mapped offset (64 PB if in sector)
uint32_t zeroed : 1; // indicating a zero-filled segment
uint8_t tag;
const static uint64_t MAX_MOFFSET = (1UL << 55) - 1;
uint16_t tag; // layer index (up to 65535 layers)
const static uint64_t MAX_MOFFSET = (1UL << 47) - 1;

SegmentMapping() {
}
SegmentMapping(uint64_t loffset, uint32_t length, uint64_t moffset, uint8_t tag = 0)
SegmentMapping(uint64_t loffset, uint32_t length, uint64_t moffset, uint16_t tag = 0)
: Segment{loffset, length}, moffset(moffset), zeroed(0), tag(tag) {
assert(length <= Segment::MAX_LENGTH);
}
Expand Down Expand Up @@ -186,7 +186,7 @@ extern "C" IMemoryIndex *merge_memory_indexes(const IMemoryIndex **pindexes, std
// were one single index; inserting into a combo effectively inserting into the index0 part;
// the mapped offset must be within [moffset_begin, moffset_end)
extern "C" IComboIndex *create_combo_index(IMemoryIndex0 *index0, const IMemoryIndex *index,
uint8_t ro_index_count, bool ownership);
uint16_t ro_index_count, bool ownership);

// compress raw index array by mergeing adjacent continuous mappings
// returning compressed size of the array
Expand Down
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