Dbid feature

Summary:
Create a new type of file on startup if it doesn't already exist called DBID.
This will store a unique number generated from boost library's uuid header file.
The use-case is to identify the case of a db losing all its data and coming back up either empty or from an image(backup/live replica's recovery)
the key point to note is that DBID is not stored in a backup or db snapshot
It's preferable to use Boost for uuid because:
1) A non-standard way of generating uuid is not good
2) /proc/sys/kernel/random/uuid generates a uuid but only on linux environments and the solution would not be clean
3) c++ doesn't have any direct way to get a uuid
4) Boost is a very good library that was already having linkage in rocksdb from third-party
Note: I had to update the TOOLCHAIN_REV in build files to get latest verison of boost from third-party as the older version had a bug.
I had to put Wno-uninitialized in Makefile because boost-1.51 has an unitialized variable and rocksdb would not comiple otherwise. Latet open-source for boost is 1.54 but is not there in third-party. I have notified the concerned people in fbcode about it.
@kailiu : While releasing to third-party, an additional dependency will need to be created for boost in TARGETS file. I can help identify.

Test Plan:
Expand db_test to test 2 cases
1) Restarting db with Id file present - verify that no change to Id
2)Restarting db with Id file deleted - verify that a different Id is there after reopen
Also run make all check

Reviewers: dhruba, haobo, kailiu, sdong

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13587
main
Mayank Agarwal 11 years ago
parent ae8e0770b4
commit 9b50106f9a
  1. 17
      build_tools/build_detect_platform
  2. 15
      build_tools/fbcode.clang31.sh
  3. 15
      build_tools/fbcode.gcc471.sh
  4. 8
      db/db_impl.cc
  5. 34
      db/db_test.cc
  6. 5
      db/deletefile_test.cc
  7. 24
      db/filename.cc
  8. 10
      db/filename.h
  9. 3
      include/rocksdb/env.h
  10. 19
      util/env_posix.cc

@ -134,14 +134,6 @@ $PWD/build_tools/build_detect_version
# of all files matching either rule, so we need to append -print to make the # of all files matching either rule, so we need to append -print to make the
# prune take effect. # prune take effect.
DIRS="util db table utilities" DIRS="util db table utilities"
if test "$USE_THRIFT"; then
DIRS="$DIRS thrift/server_utils.cpp thrift/gen-cpp "
THRIFTSERVER=leveldb_server
fi
if test "$USE_SCRIBE"; then
DIRS="$DIRS scribe "
fi
set -f # temporarily disable globbing so that our patterns arent expanded set -f # temporarily disable globbing so that our patterns arent expanded
PRUNE_TEST="-name *test*.cc -prune" PRUNE_TEST="-name *test*.cc -prune"
@ -227,14 +219,6 @@ if test "$USE_HDFS"; then
PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS $HDFS_LDFLAGS" PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS $HDFS_LDFLAGS"
fi fi
# shall we build thrift server or scribe logger
if test "$USE_THRIFT" || test "$USE_SCRIBE" ; then
THRIFT_CCFLAGS=" -I./thrift -I./thrift/gen-cpp -I./thrift/lib/cpp -I/usr/include -std=gnu++0x"
THRIFT_LDFLAGS=" -lexample -lserver -lthrift_base -ltransport -lthrift_exception -lutil -L./thrift/libs "
COMMON_FLAGS="$COMMON_FLAGS $THRIFT_CCFLAGS"
PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS $THRIFT_LDFLAGS"
fi
# if Intel SSE instruction set is supported, set USE_SSE=" -msse -msse4.2 " # if Intel SSE instruction set is supported, set USE_SSE=" -msse -msse4.2 "
COMMON_FLAGS="$COMMON_FLAGS $USE_SSE" COMMON_FLAGS="$COMMON_FLAGS $USE_SSE"
@ -254,5 +238,4 @@ echo "PLATFORM_SHARED_CFLAGS=$PLATFORM_SHARED_CFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_EXT=$PLATFORM_SHARED_EXT" >> $OUTPUT echo "PLATFORM_SHARED_EXT=$PLATFORM_SHARED_EXT" >> $OUTPUT
echo "PLATFORM_SHARED_LDFLAGS=$PLATFORM_SHARED_LDFLAGS" >> $OUTPUT echo "PLATFORM_SHARED_LDFLAGS=$PLATFORM_SHARED_LDFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_VERSIONED=$PLATFORM_SHARED_VERSIONED" >> $OUTPUT echo "PLATFORM_SHARED_VERSIONED=$PLATFORM_SHARED_VERSIONED" >> $OUTPUT
echo "THRIFTSERVER=$THRIFTSERVER" >> $OUTPUT
echo "EXEC_LDFLAGS=$EXEC_LDFLAGS" >> $OUTPUT echo "EXEC_LDFLAGS=$EXEC_LDFLAGS" >> $OUTPUT

@ -4,21 +4,16 @@
# fbcode settings. It uses the latest g++ compiler and also # fbcode settings. It uses the latest g++ compiler and also
# uses jemalloc # uses jemalloc
TOOLCHAIN_REV=f365dbeae46a30414a2874a6f45e73e10f1caf7d TOOLCHAIN_REV=fbe3b095a4cc4a3713730050d182b7b4a80c342f
TOOLCHAIN_EXECUTABLES="/mnt/gvfs/third-party/$TOOLCHAIN_REV/centos5.2-native" TOOLCHAIN_EXECUTABLES="/mnt/gvfs/third-party/$TOOLCHAIN_REV/centos5.2-native"
TOOLCHAIN_LIB_BASE="/mnt/gvfs/third-party/$TOOLCHAIN_REV/gcc-4.7.1-glibc-2.14.1" TOOLCHAIN_LIB_BASE="/mnt/gvfs/third-party/$TOOLCHAIN_REV/gcc-4.7.1-glibc-2.14.1"
TOOL_JEMALLOC=jemalloc-3.0.0/2f45f3a TOOL_JEMALLOC=jemalloc-3.3.1/9202ce3
GLIBC_RUNTIME_PATH=/usr/local/fbcode/gcc-4.7.1-glibc-2.14.1 GLIBC_RUNTIME_PATH=/usr/local/fbcode/gcc-4.7.1-glibc-2.14.1
# location of snappy headers and libraries # location of snappy headers and libraries
SNAPPY_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/snappy/snappy-1.0.3/7518bbe/include" SNAPPY_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/snappy/snappy-1.0.3/7518bbe/include"
SNAPPY_LIBS=" $TOOLCHAIN_LIB_BASE/snappy/snappy-1.0.3/7518bbe/lib/libsnappy.a" SNAPPY_LIBS=" $TOOLCHAIN_LIB_BASE/snappy/snappy-1.0.3/7518bbe/lib/libsnappy.a"
# location of boost headers and libraries
THRIFT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/boost/boost-1.48.0/bef9365/include -std=gnu++0x"
THRIFT_INCLUDE+=" -I./thrift -I./thrift/gen-cpp -I./thrift/lib/cpp"
THRIFT_LIBS=" -L $TOOLCHAIN_LIB_BASE/boost/boost-1.48.0/bef9365/lib"
# location of libevent # location of libevent
LIBEVENT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/include" LIBEVENT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/include"
LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib" LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib"
@ -27,7 +22,7 @@ LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib"
export USE_SSE=" -msse -msse4.2 " export USE_SSE=" -msse -msse4.2 "
CC="$TOOLCHAIN_EXECUTABLES/clang/clang-3.1/6ca8a59/bin/clang $CLANG_INCLUDES" CC="$TOOLCHAIN_EXECUTABLES/clang/clang-3.1/6ca8a59/bin/clang $CLANG_INCLUDES"
CXX="$TOOLCHAIN_EXECUTABLES/clang/clang-3.1/6ca8a59/bin/clang++ $CLANG_INCLUDES $JINCLUDE $SNAPPY_INCLUDE $THRIFT_INCLUDE $LIBEVENT_INCLUDE" CXX="$TOOLCHAIN_EXECUTABLES/clang/clang-3.1/6ca8a59/bin/clang++ $CLANG_INCLUDES $JINCLUDE $SNAPPY_INCLUDE $LIBEVENT_INCLUDE"
AR=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ar AR=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ar
RANLIB=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ranlib RANLIB=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ranlib
@ -37,8 +32,8 @@ CXXFLAGS="$CFLAGS -nostdinc++ -std=gnu++0x"
CFLAGS+=" -I $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/include -DHAVE_JEMALLOC" CFLAGS+=" -I $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/include -DHAVE_JEMALLOC"
EXEC_LDFLAGS=" -Wl,--whole-archive $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.a" EXEC_LDFLAGS=" -Wl,--whole-archive $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.a"
EXEC_LDFLAGS+=" -Wl,--no-whole-archive $TOOLCHAIN_LIB_BASE/libunwind/libunwind-1.0.1/91ddd43/lib/libunwind.a" EXEC_LDFLAGS+=" -Wl,--no-whole-archive $TOOLCHAIN_LIB_BASE/libunwind/libunwind-1.0.1/350336c/lib/libunwind.a"
EXEC_LDFLAGS+=" $HDFSLIB $SNAPPY_LIBS $THRIFT_LIBS $LIBEVENT_LIBS" EXEC_LDFLAGS+=" $HDFSLIB $SNAPPY_LIBS $LIBEVENT_LIBS"
EXEC_LDFLAGS+=" -Wl,--dynamic-linker,$GLIBC_RUNTIME_PATH/lib/ld-linux-x86-64.so.2" EXEC_LDFLAGS+=" -Wl,--dynamic-linker,$GLIBC_RUNTIME_PATH/lib/ld-linux-x86-64.so.2"
EXEC_LDFLAGS+=" -B$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin" EXEC_LDFLAGS+=" -B$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin"

@ -4,10 +4,10 @@
# fbcode settings. It uses the latest g++ compiler and also # fbcode settings. It uses the latest g++ compiler and also
# uses jemalloc # uses jemalloc
TOOLCHAIN_REV=83eb773e262fa705eaebbf3de40db71d53fabf2e TOOLCHAIN_REV=fbe3b095a4cc4a3713730050d182b7b4a80c342f
TOOLCHAIN_EXECUTABLES="/mnt/gvfs/third-party/$TOOLCHAIN_REV/centos5.2-native" TOOLCHAIN_EXECUTABLES="/mnt/gvfs/third-party/$TOOLCHAIN_REV/centos5.2-native"
TOOLCHAIN_LIB_BASE="/mnt/gvfs/third-party/$TOOLCHAIN_REV/gcc-4.7.1-glibc-2.14.1" TOOLCHAIN_LIB_BASE="/mnt/gvfs/third-party/$TOOLCHAIN_REV/gcc-4.7.1-glibc-2.14.1"
TOOL_JEMALLOC=jemalloc-3.3.1/2f45f3a TOOL_JEMALLOC=jemalloc-3.3.1/9202ce3
# location of libhdfs libraries # location of libhdfs libraries
if test "$USE_HDFS"; then if test "$USE_HDFS"; then
@ -27,11 +27,6 @@ SNAPPY_LIBS=" $TOOLCHAIN_LIB_BASE/snappy/snappy-1.0.3/7518bbe/lib/libsnappy.a"
ZLIB_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/zlib/zlib-1.2.5/91ddd43/include" ZLIB_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/zlib/zlib-1.2.5/91ddd43/include"
ZLIB_LIBS=" $TOOLCHAIN_LIB_BASE/zlib/zlib-1.2.5/91ddd43/lib/libz.a" ZLIB_LIBS=" $TOOLCHAIN_LIB_BASE/zlib/zlib-1.2.5/91ddd43/lib/libz.a"
# location of boost headers and libraries
THRIFT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/boost/boost-1.48.0/2a0840d/include"
THRIFT_INCLUDE+=" -I./thrift -I./thrift/gen-cpp -I./thrift/lib/cpp"
THRIFT_LIBS=" -L $TOOLCHAIN_LIB_BASE/boost/boost-1.48.0/2a0840d/lib"
# location of libevent # location of libevent
LIBEVENT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/include" LIBEVENT_INCLUDE=" -I $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/include"
LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib" LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib"
@ -40,7 +35,7 @@ LIBEVENT_LIBS=" -L $TOOLCHAIN_LIB_BASE/libevent/libevent-1.4.14b/91ddd43/lib"
export USE_SSE=" -msse -msse4.2 " export USE_SSE=" -msse -msse4.2 "
CC="$TOOLCHAIN_EXECUTABLES/gcc/gcc-4.7.1-glibc-2.14.1/bin/gcc" CC="$TOOLCHAIN_EXECUTABLES/gcc/gcc-4.7.1-glibc-2.14.1/bin/gcc"
CXX="$TOOLCHAIN_EXECUTABLES/gcc/gcc-4.7.1-glibc-2.14.1/bin/g++ $JINCLUDE $SNAPPY_INCLUDE $ZLIB_INCLUDE $THRIFT_INCLUDE $LIBEVENT_INCLUDE" CXX="$TOOLCHAIN_EXECUTABLES/gcc/gcc-4.7.1-glibc-2.14.1/bin/g++ $JINCLUDE $SNAPPY_INCLUDE $ZLIB_INCLUDE $LIBEVENT_INCLUDE"
AR=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ar AR=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ar
RANLIB=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ranlib RANLIB=$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/da39a3e/bin/ranlib
@ -48,8 +43,8 @@ CFLAGS="-B$TOOLCHAIN_EXECUTABLES/binutils/binutils-2.21.1/bin/gold -m64 -mtune=g
CFLAGS+=" -I $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/include -DHAVE_JEMALLOC" CFLAGS+=" -I $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/include -DHAVE_JEMALLOC"
EXEC_LDFLAGS=" -Wl,--whole-archive $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.a" EXEC_LDFLAGS=" -Wl,--whole-archive $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.a"
EXEC_LDFLAGS+=" -Wl,--no-whole-archive $TOOLCHAIN_LIB_BASE/libunwind/libunwind-1.0.1/91ddd43/lib/libunwind.a" EXEC_LDFLAGS+=" -Wl,--no-whole-archive $TOOLCHAIN_LIB_BASE/libunwind/libunwind-1.0.1/350336c/lib/libunwind.a"
EXEC_LDFLAGS+=" $HDFSLIB $SNAPPY_LIBS $ZLIB_LIBS $THRIFT_LIBS $LIBEVENT_LIBS" EXEC_LDFLAGS+=" $HDFSLIB $SNAPPY_LIBS $ZLIB_LIBS $LIBEVENT_LIBS"
PLATFORM_LDFLAGS="-L$TOOLCHAIN_LIB_BASE/libgcc/libgcc-4.7.1/afc21dc/lib -L$TOOLCHAIN_LIB_BASE/glibc/glibc-2.14.1/99df8fc/lib" PLATFORM_LDFLAGS="-L$TOOLCHAIN_LIB_BASE/libgcc/libgcc-4.7.1/afc21dc/lib -L$TOOLCHAIN_LIB_BASE/glibc/glibc-2.14.1/99df8fc/lib"

@ -509,6 +509,7 @@ void DBImpl::PurgeObsoleteFiles(DeletionState& state) {
break; break;
case kCurrentFile: case kCurrentFile:
case kDBLockFile: case kDBLockFile:
case kIdentityFile:
case kMetaDatabase: case kMetaDatabase:
keep = true; keep = true;
break; break;
@ -639,6 +640,13 @@ Status DBImpl::Recover(VersionEdit* edit, MemTable* external_table,
dbname_, "exists (error_if_exists is true)"); dbname_, "exists (error_if_exists is true)");
} }
} }
// Check for the IDENTITY file and create it if not there
if (!env_->FileExists(IdentityFileName(dbname_))) {
s = SetIdentityFile(env_, dbname_);
if (!s.ok()) {
return s;
}
}
} }
Status s = versions_->Recover(); Status s = versions_->Recover();

@ -1630,12 +1630,12 @@ TEST(DBTest, ManifestRollOver) {
ASSERT_OK(Put("manifest_key1", std::string(1000, '1'))); ASSERT_OK(Put("manifest_key1", std::string(1000, '1')));
ASSERT_OK(Put("manifest_key2", std::string(1000, '2'))); ASSERT_OK(Put("manifest_key2", std::string(1000, '2')));
ASSERT_OK(Put("manifest_key3", std::string(1000, '3'))); ASSERT_OK(Put("manifest_key3", std::string(1000, '3')));
uint64_t manifest_before_fulsh = uint64_t manifest_before_flush =
dbfull()->TEST_Current_Manifest_FileNo(); dbfull()->TEST_Current_Manifest_FileNo();
dbfull()->Flush(FlushOptions()); // This should trigger LogAndApply. dbfull()->Flush(FlushOptions()); // This should trigger LogAndApply.
uint64_t manifest_after_flush = uint64_t manifest_after_flush =
dbfull()->TEST_Current_Manifest_FileNo(); dbfull()->TEST_Current_Manifest_FileNo();
ASSERT_GT(manifest_after_flush, manifest_before_fulsh); ASSERT_GT(manifest_after_flush, manifest_before_flush);
Reopen(&options); Reopen(&options);
ASSERT_GT(dbfull()->TEST_Current_Manifest_FileNo(), ASSERT_GT(dbfull()->TEST_Current_Manifest_FileNo(),
manifest_after_flush); manifest_after_flush);
@ -1647,6 +1647,36 @@ TEST(DBTest, ManifestRollOver) {
} while (ChangeCompactOptions()); } while (ChangeCompactOptions());
} }
TEST(DBTest, IdentityAcrossRestarts) {
do {
std::string idfilename = IdentityFileName(dbname_);
unique_ptr<SequentialFile> idfile;
const EnvOptions soptions;
ASSERT_OK(env_->NewSequentialFile(idfilename, &idfile, soptions));
char buffer1[100];
Slice id1;
ASSERT_OK(idfile->Read(100, &id1, buffer1));
Options options = CurrentOptions();
Reopen(&options);
char buffer2[100];
Slice id2;
ASSERT_OK(env_->NewSequentialFile(idfilename, &idfile, soptions));
ASSERT_OK(idfile->Read(100, &id2, buffer2));
// id1 should match id2 because identity was not regenerated
ASSERT_EQ(id1.ToString(), id2.ToString());
ASSERT_OK(env_->DeleteFile(idfilename));
Reopen(&options);
char buffer3[100];
Slice id3;
ASSERT_OK(env_->NewSequentialFile(idfilename, &idfile, soptions));
ASSERT_OK(idfile->Read(100, &id3, buffer3));
// id1 should NOT match id2 because identity was regenerated
ASSERT_NE(id1.ToString(0), id3.ToString());
} while (ChangeCompactOptions());
}
TEST(DBTest, RecoverWithLargeLog) { TEST(DBTest, RecoverWithLargeLog) {
do { do {
{ {

@ -14,12 +14,11 @@
#include "db/write_batch_internal.h" #include "db/write_batch_internal.h"
#include "util/testharness.h" #include "util/testharness.h"
#include "util/testutil.h" #include "util/testutil.h"
#include "boost/lexical_cast.hpp"
#include "rocksdb/env.h" #include "rocksdb/env.h"
#include <vector> #include <vector>
#include <boost/algorithm/string.hpp>
#include <stdlib.h> #include <stdlib.h>
#include <map> #include <map>
#include <string>
namespace rocksdb { namespace rocksdb {
@ -62,7 +61,7 @@ class DeleteFileTest {
options.sync = false; options.sync = false;
ReadOptions roptions; ReadOptions roptions;
for (int i = startkey; i < (numkeys + startkey) ; i++) { for (int i = startkey; i < (numkeys + startkey) ; i++) {
std::string temp = boost::lexical_cast<std::string>(i); std::string temp = std::to_string(i);
Slice key(temp); Slice key(temp);
Slice value(temp); Slice value(temp);
ASSERT_OK(db_->Put(options, key, value)); ASSERT_OK(db_->Put(options, key, value));

@ -127,7 +127,12 @@ std::string MetaDatabaseName(const std::string& dbname, uint64_t number) {
return dbname + buf; return dbname + buf;
} }
std::string IdentityFileName(const std::string& dbname) {
return dbname + "/IDENTITY";
}
// Owned filenames have the form: // Owned filenames have the form:
// dbname/IDENTITY
// dbname/CURRENT // dbname/CURRENT
// dbname/LOCK // dbname/LOCK
// dbname/LOG // dbname/LOG
@ -143,7 +148,10 @@ bool ParseFileName(const std::string& fname,
if (fname.length() > 1 && fname[0] == '/') { if (fname.length() > 1 && fname[0] == '/') {
rest.remove_prefix(1); rest.remove_prefix(1);
} }
if (rest == "CURRENT") { if (rest == "IDENTITY") {
*number = 0;
*type = kIdentityFile;
} else if (rest == "CURRENT") {
*number = 0; *number = 0;
*type = kCurrentFile; *type = kCurrentFile;
} else if (rest == "LOCK") { } else if (rest == "LOCK") {
@ -223,4 +231,18 @@ Status SetCurrentFile(Env* env, const std::string& dbname,
return s; return s;
} }
Status SetIdentityFile(Env* env, const std::string& dbname) {
std::string id = env->GenerateUniqueId();
assert(!id.empty());
std::string tmp = TempFileName(dbname, id.size());
Status s = WriteStringToFileSync(env, id, tmp);
if (s.ok()) {
s = env->RenameFile(tmp, IdentityFileName(dbname));
}
if (!s.ok()) {
env->DeleteFile(tmp);
}
return s;
}
} // namespace rocksdb } // namespace rocksdb

@ -28,7 +28,8 @@ enum FileType {
kCurrentFile, kCurrentFile,
kTempFile, kTempFile,
kInfoLogFile, // Either the current one, or an old one kInfoLogFile, // Either the current one, or an old one
kMetaDatabase kMetaDatabase,
kIdentityFile
}; };
// Return the name of the log file with the specified number // Return the name of the log file with the specified number
@ -82,6 +83,11 @@ extern std::string OldInfoLogFileName(const std::string& dbname, uint64_t ts,
extern std::string MetaDatabaseName(const std::string& dbname, extern std::string MetaDatabaseName(const std::string& dbname,
uint64_t number); uint64_t number);
// Return the name of the Identity file which stores a unique number for the db
// that will get regenerated if the db loses all its data and is recreated fresh
// either from a backup-image or empty
extern std::string IdentityFileName(const std::string& dbname);
// If filename is a rocksdb file, store the type of the file in *type. // If filename is a rocksdb file, store the type of the file in *type.
// The number encoded in the filename is stored in *number. If the // The number encoded in the filename is stored in *number. If the
// filename was successfully parsed, returns true. Else return false. // filename was successfully parsed, returns true. Else return false.
@ -94,5 +100,7 @@ extern bool ParseFileName(const std::string& filename,
extern Status SetCurrentFile(Env* env, const std::string& dbname, extern Status SetCurrentFile(Env* env, const std::string& dbname,
uint64_t descriptor_number); uint64_t descriptor_number);
// Make the IDENTITY file for the db
extern Status SetIdentityFile(Env* env, const std::string& dbname);
} // namespace rocksdb } // namespace rocksdb

@ -233,6 +233,9 @@ class Env {
// Converts seconds-since-Jan-01-1970 to a printable string // Converts seconds-since-Jan-01-1970 to a printable string
virtual std::string TimeToString(uint64_t time) = 0; virtual std::string TimeToString(uint64_t time) = 0;
// Generates a unique id that can be used to identify a db
virtual std::string GenerateUniqueId();
private: private:
// No copying allowed // No copying allowed
Env(const Env&); Env(const Env&);

@ -1386,6 +1386,25 @@ void PosixEnv::StartThread(void (*function)(void* arg), void* arg) {
} // namespace } // namespace
std::string Env::GenerateUniqueId() {
std::string uuid_file = "/proc/sys/kernel/random/uuid";
if (FileExists(uuid_file)) {
std::string uuid;
Status s = ReadFileToString(this, uuid_file, &uuid);
if (s.ok()) {
return uuid;
}
}
// Could not read uuid_file - generate uuid using "nanos-random"
Random64 r(time(nullptr));
uint64_t random_uuid_portion =
r.Uniform(std::numeric_limits<uint64_t>::max());
uint64_t nanos_uuid_portion = NowNanos();
char uuid2[200];
snprintf(uuid2, 200, "%lx-%lx", nanos_uuid_portion, random_uuid_portion);
return uuid2;
}
Env* Env::Default() { Env* Env::Default() {
static PosixEnv default_env; static PosixEnv default_env;
return &default_env; return &default_env;

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