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author | giorgio <giorgio@13f79535-47bb-0310-9956-ffa450edef68> | 2012-09-05 08:31:30 +0000 |
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committer | giorgio <giorgio@13f79535-47bb-0310-9956-ffa450edef68> | 2012-09-05 08:31:30 +0000 |
commit | c9bfccc35345ce58fb5774d4b0b6a9868b262c0a (patch) | |
tree | fe84dd4b90f2acd0b933550b6978094926c1d733 /sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp | |
parent | 5ddabdaf1ff856aae79dadc045ef2aeff08c7887 (diff) |
git-svn-id: http://svn.us.apache.org/repos/asf/tuscany@1381061 13f79535-47bb-0310-9956-ffa450edef68
Diffstat (limited to 'sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp')
-rw-r--r-- | sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp | 488 |
1 files changed, 488 insertions, 0 deletions
diff --git a/sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp b/sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp new file mode 100644 index 0000000000..68be0a09dc --- /dev/null +++ b/sca-cpp/branches/lightweight-sca/components/constdb/tinycdb.hpp @@ -0,0 +1,488 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +/* $Rev$ $Date$ */ + +#ifndef tuscany_tinycdb_hpp +#define tuscany_tinycdb_hpp + +#include <fcntl.h> +#include <unistd.h> +#include <sys/stat.h> +#include <cdb.h> + +#include "string.hpp" +#include "list.hpp" +#include "value.hpp" +#include "monad.hpp" +#include "../../modules/scheme/eval.hpp" + +namespace tuscany { +namespace tinycdb { + +/** + * A reallocatable buffer. + */ +class buffer { +public: + operator void*() const throw() { + return buf; + } + + operator unsigned char*() const throw() { + return (unsigned char*)buf; + } + + operator char*() const throw() { + return (char*)buf; + } + +private: + buffer(const unsigned int size, void* buf) : size(size), buf(buf) { + } + + unsigned int size; + void* buf; + + friend const buffer mkbuffer(const unsigned int sz); + friend const buffer mkbuffer(const buffer& b, const unsigned int newsz); + friend const bool free(const buffer& b); +}; + +/** + * Make a new buffer. + */ +const buffer mkbuffer(const unsigned int sz) { + return buffer(sz, malloc(sz)); +} + +/** + * Make a new buffer by reallocating an existing one. + */ +const buffer mkbuffer(const buffer& b, const unsigned int sz) { + if (sz <= b.size) + return b; + return buffer(sz, realloc(b.buf, sz)); +} + +/** + * Free a buffer. + */ +const bool free(const buffer&b) { + ::free(b.buf); + return true; +} + +/** + * Convert a database name to an absolute path. + */ +const string absdbname(const string& name) { + if (length(name) == 0 || c_str(name)[0] == '/') + return name; + char cwd[512]; + if (getcwd(cwd, sizeof(cwd)) == NULL) + return name; + return string(cwd) + "/" + name; +} + +/** + * Represents a TinyCDB connection. + */ +class TinyCDB { +public: + TinyCDB() : owner(false), fd(-1) { + st.st_ino = 0; + } + + TinyCDB(const string& name) : owner(true), name(absdbname(name)), fd(-1) { + debug(name, "tinycdb::tinycdb::name"); + st.st_ino = 0; + } + + TinyCDB(const TinyCDB& c) : owner(false), name(c.name), fd(c.fd) { + debug("tinycdb::tinycdb::copy"); + st.st_ino = c.st.st_ino; + } + + const TinyCDB& operator=(const TinyCDB& c) { + debug("tinycdb::tinycdb::operator="); + if(this == &c) + return *this; + owner = false; + name = c.name; + fd = c.fd; + st.st_ino = c.st.st_ino; + return *this; + } + + ~TinyCDB() { + if (!owner) + return; + if (fd == -1) + return; + close(fd); + } + +private: + bool owner; + string name; + int fd; + struct stat st; + + friend const string dbname(const TinyCDB& cdb); + friend const failable<int> cdbopen(TinyCDB& cdb); + friend const failable<bool> cdbclose(TinyCDB& cdb); +}; + +/** + * Return the name of the database. + */ +const string dbname(const TinyCDB& cdb) { + return cdb.name; +} + +/** + * Open a database. + */ +const failable<int> cdbopen(TinyCDB& cdb) { + + // Get database file serial number + struct stat st; + const int s = stat(c_str(cdb.name), &st); + if (s == -1) + return mkfailure<int>(string("Couldn't tinycdb read database stat: ") + cdb.name); + + // Open database for the first time + if (cdb.fd == -1) { + cdb.fd = open(c_str(cdb.name), O_RDONLY); + if (cdb.fd == -1) + return mkfailure<int>(string("Couldn't open tinycdb database file: ") + cdb.name); + debug(cdb.fd, "tinycdb::open::fd"); + cdb.st = st; + return cdb.fd; + } + + // Close and reopen database after a change + if (st.st_ino != cdb.st.st_ino) { + + // Close current fd + close(cdb.fd); + + // Reopen database + const int newfd = open(c_str(cdb.name), O_RDONLY); + if (newfd == -1) + return mkfailure<int>(string("Couldn't open tinycdb database file: ") + cdb.name); + if (newfd == cdb.fd) { + debug(cdb.fd, "tinycdb::open::fd"); + cdb.st = st; + return cdb.fd; + } + + // We got a different fd, dup it to the current fd then close it + if (fcntl(newfd, F_DUPFD, cdb.fd) == -1) + return mkfailure<int>(string("Couldn't dup tinycdb database file handle: ") + cdb.name); + close(newfd); + + debug(cdb.fd, "tinycdb::open::fd"); + cdb.st = st; + return cdb.fd; + } + + // No change, just return the current fd + return cdb.fd; +} + +/** + * Close a database. + */ +const failable<bool> cdbclose(TinyCDB& cdb) { + close(cdb.fd); + cdb.fd = -1; + return true; +} + +/** + * Rewrite a database. The given update function is passed each entry, and + * can return true to let the entry added to the new db, false to skip the + * entry, or a failure. + */ +const failable<bool> rewrite(const lambda<failable<bool>(buffer& buf, const unsigned int klen, const unsigned int vlen)>& update, const lambda<failable<bool>(struct cdb_make&)>& finish, buffer& buf, const int tmpfd, TinyCDB& cdb) { + + // Initialize new db structure + struct cdb_make cdbm; + cdb_make_start(&cdbm, tmpfd); + + // Open existing db + failable<int> ffd = cdbopen(cdb); + if (!hasContent(ffd)) + return mkfailure<bool>(ffd); + const int fd = content(ffd); + + // Read the db header + unsigned int pos = 0; + if (lseek(fd, 0, SEEK_SET) != 0) + return mkfailure<bool>("Couldn't seek to tinycdb database start"); + if (::read(fd, buf, 2048) != 2048) + return mkfailure<bool>("Couldn't read tinycdb database header"); + pos += 2048; + unsigned int eod = cdb_unpack(buf); + debug(pos, "tinycdb::rewrite::eod"); + + // Read and add the existing entries + while(pos < eod) { + if (eod - pos < 8) + return mkfailure<bool>("Invalid tinycdb database format, couldn't read entry header"); + if (::read(fd, buf, 8) != 8) + return mkfailure<bool>("Couldn't read tinycdb entry header"); + pos += 8; + unsigned int klen = cdb_unpack(buf); + unsigned int vlen = cdb_unpack(((unsigned char*)buf) + 4); + unsigned int elen = klen + vlen; + + // Read existing entry + buf = mkbuffer(buf, elen); + if (eod - pos < elen) + return mkfailure<bool>("Invalid tinycdb database format, couldn't read entry"); + if ((unsigned int)::read(fd, buf, elen) != elen) + return mkfailure<bool>("Couldn't read tinycdb entry"); + pos += elen; + + // Apply the update function to the entry + debug(string((char*)buf, klen), "tinycdb::rewrite::existing key"); + debug(string(((char*)buf) + klen, vlen), "tinycdb::rewrite::existing value"); + const failable<bool> u = update(buf, klen, vlen); + if (!hasContent(u)) + return u; + + // Skip the entry if the update function returned false + if (u == false) + continue; + + // Add the entry to the new db + if (cdb_make_add(&cdbm, buf, klen, ((unsigned char*)buf)+klen, vlen) == -1) + return mkfailure<bool>("Couldn'tt add tinycdb entry"); + } + if (pos != eod) + return mkfailure<bool>("Invalid tinycdb database format"); + + // Call the finish function + const failable<bool> f = finish(cdbm); + if (!hasContent(f)) + return f; + + // Save the new db + if (cdb_make_finish(&cdbm) == -1) + return mkfailure<bool>("Couldn't save tinycdb database"); + + return true; +} + +const failable<bool> rewrite(const lambda<failable<bool>(buffer& buf, const unsigned int klen, const unsigned int vlen)>& update, const lambda<failable<bool>(struct cdb_make&)>& finish, TinyCDB& cdb) { + + // Create a new temporary db file + string tmpname = dbname(cdb) + ".XXXXXX"; + int tmpfd = mkstemp(const_cast<char*>(c_str(tmpname))); + if (tmpfd == -1) + return mkfailure<bool>("Couldn't create temporary tinycdb database"); + + // Rewrite the db, apply the update function to each entry + buffer buf = mkbuffer(2048); + const failable<bool> r = rewrite(update, finish, buf, tmpfd, cdb); + if (!hasContent(r)) { + close(tmpfd); + free(buf); + return r; + } + + // Atomically replace the db and reopen it in read mode + if (rename(c_str(tmpname), c_str(dbname(cdb))) == -1) + return mkfailure<bool>("Couldn't rename temporary tinycdb database"); + cdbclose(cdb); + failable<int> ffd = cdbopen(cdb); + if (!hasContent(ffd)) + return mkfailure<bool>(ffd); + + return true; +} + +/** + * Post a new item to the database. + */ +struct postUpdate { + const string ks; + postUpdate(const string& ks) : ks(ks) { + } + const failable<bool> operator()(buffer& buf, const unsigned int klen, unused const unsigned int vlen) const { + if (ks == string((char*)buf, klen)) + return mkfailure<bool>("Key already exists in tinycdb database"); + return true; + } +}; + +struct postFinish { + const string ks; + const string vs; + postFinish(const string& ks, const string& vs) : ks(ks), vs(vs) { + } + const failable<bool> operator()(struct cdb_make& cdbm) const { + if (cdb_make_add(&cdbm, c_str(ks), (unsigned int)length(ks), c_str(vs), (unsigned int)length(vs)) == -1) + return mkfailure<bool>(string("Couldn't add tinycdb entry: ") + ks); + return true; + } +}; + +const failable<bool> post(const value& key, const value& val, TinyCDB& cdb) { + debug(key, "tinycdb::post::key"); + debug(val, "tinycdb::post::value"); + debug(dbname(cdb), "tinycdb::post::dbname"); + + const string ks(scheme::writeValue(key)); + const string vs(scheme::writeValue(val)); + + // Process each entry and detect existing key + const lambda<failable<bool>(buffer& buf, const unsigned int klen, const unsigned int vlen)> update = postUpdate(ks); + + // Add the new entry to the db + const lambda<failable<bool>(struct cdb_make& cdbm)> finish = postFinish(ks, vs); + + // Rewrite the db + const failable<bool> r = rewrite(update, finish, cdb); + debug(r, "tinycdb::post::result"); + return r; +} + +/** + * Update an item in the database. If the item doesn't exist it is added. + */ +struct putUpdate { + const string ks; + putUpdate(const string& ks) : ks(ks) { + } + const failable<bool> operator()(buffer& buf, const unsigned int klen, unused const unsigned int vlen) const { + if (ks == string((char*)buf, klen)) + return false; + return true; + } +}; + +struct putFinish { + const string ks; + const string vs; + putFinish(const string& ks, const string& vs) : ks(ks), vs(vs) { + } + const failable<bool> operator()(struct cdb_make& cdbm) const { + if (cdb_make_add(&cdbm, c_str(ks), (unsigned int)length(ks), c_str(vs), (unsigned int)length(vs)) == -1) + return mkfailure<bool>(string("Couldn't add tinycdb entry: ") + ks); + return true; + } +}; + +const failable<bool> put(const value& key, const value& val, TinyCDB& cdb) { + debug(key, "tinycdb::put::key"); + debug(val, "tinycdb::put::value"); + debug(dbname(cdb), "tinycdb::put::dbname"); + + const string ks(scheme::writeValue(key)); + const string vs(scheme::writeValue(val)); + + // Process each entry and skip existing key + const lambda<failable<bool>(buffer& buf, const unsigned int klen, const unsigned int vlen)> update = putUpdate(ks); + + // Add the new entry to the db + const lambda<failable<bool>(struct cdb_make& cdbm)> finish = putFinish(ks, vs); + + // Rewrite the db + const failable<bool> r = rewrite(update, finish, cdb); + debug(r, "tinycdb::put::result"); + return r; +} + +/** + * Get an item from the database. + */ +const failable<value> get(const value& key, TinyCDB& cdb) { + debug(key, "tinycdb::get::key"); + debug(dbname(cdb), "tinycdb::get::dbname"); + + const failable<int> ffd = cdbopen(cdb); + if (!hasContent(ffd)) + return mkfailure<value>(ffd); + const int fd = content(ffd); + + const string ks(scheme::writeValue(key)); + + cdbi_t vlen; + if (cdb_seek(fd, c_str(ks), (unsigned int)length(ks), &vlen) <= 0) { + ostringstream os; + os << "Couldn't get tinycdb entry: " << key; + return mkfailure<value>(str(os), 404, false); + } + char* data = gc_cnew(vlen + 1); + cdb_bread(fd, data, vlen); + data[vlen] = '\0'; + const value val(scheme::readValue(string(data))); + + debug(val, "tinycdb::get::result"); + return val; +} + +/** + * Delete an item from the database + */ +struct delUpdate { + const string ks; + delUpdate(const string& ks) : ks(ks) { + } + const failable<bool> operator()(buffer& buf, const unsigned int klen, unused const unsigned int vlen) const { + if (ks == string((char*)buf, klen)) + return false; + return true; + } +}; + +struct delFinish { + delFinish() { + } + const failable<bool> operator()(unused struct cdb_make& cdbm) const { + return true; + } +}; + +const failable<bool> del(const value& key, TinyCDB& cdb) { + debug(key, "tinycdb::delete::key"); + debug(dbname(cdb), "tinycdb::delete::dbname"); + + const string ks(scheme::writeValue(key)); + + // Process each entry and skip existing key + const lambda<failable<bool>(buffer& buf, const unsigned int klen, const unsigned int vlen)> update = delUpdate(ks); + + // Nothing to do to finish + const lambda<failable<bool>(struct cdb_make& cdbm)> finish = delFinish(); + + // Rewrite the db + const failable<bool> r = rewrite(update, finish, cdb); + debug(r, "tinycdb::delete::result"); + return r; +} + +} +} + +#endif /* tuscany_tinycdb_hpp */ |