libdap++ Updated for version 3.8.2

HTTPCacheTable.cc

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00001 
00002 // -*- mode: c++; c-basic-offset:4 -*-
00003 
00004 // This file is part of libdap, A C++ implementation of the OPeNDAP Data
00005 // Access Protocol.
00006 
00007 // Copyright (c) 2002,2003 OPeNDAP, Inc.
00008 // Author: James Gallagher <jgallagher@opendap.org>
00009 //
00010 // This library is free software; you can redistribute it and/or
00011 // modify it under the terms of the GNU Lesser General Public
00012 // License as published by the Free Software Foundation; either
00013 // version 2.1 of the License, or (at your option) any later version.
00014 //
00015 // This library is distributed in the hope that it will be useful,
00016 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018 // Lesser General Public License for more details.
00019 //
00020 // You should have received a copy of the GNU Lesser General Public
00021 // License along with this library; if not, write to the Free Software
00022 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00023 //
00024 // You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
00025 
00026 #include "config.h"
00027 
00028 //#define DODS_DEBUG
00029 
00030 // TODO: Remove unneeded includes.
00031 
00032 #include <pthread.h>
00033 #include <limits.h>
00034 #include <unistd.h>   // for stat
00035 #include <sys/types.h>  // for stat and mkdir
00036 #include <sys/stat.h>
00037 
00038 #include <cstring>
00039 #include <iostream>
00040 #include <sstream>
00041 #include <algorithm>
00042 #include <iterator>
00043 #include <set>
00044 
00045 #include "Error.h"
00046 #include "InternalErr.h"
00047 #include "ResponseTooBigErr.h"
00048 #ifndef WIN32
00049 #include "SignalHandler.h"
00050 #endif
00051 #include "HTTPCacheInterruptHandler.h"
00052 #include "HTTPCacheTable.h"
00053 
00054 #include "util_mit.h"
00055 #include "debug.h"
00056 
00057 #ifdef WIN32
00058 #include <direct.h>
00059 #include <time.h>
00060 #include <fcntl.h>
00061 #define MKDIR(a,b) _mkdir((a))
00062 #define REMOVE(a) remove((a))
00063 #define MKSTEMP(a) _open(_mktemp((a)),_O_CREAT,_S_IREAD|_S_IWRITE)
00064 #define DIR_SEPARATOR_CHAR '\\'
00065 #define DIR_SEPARATOR_STR "\\"
00066 #else
00067 #define MKDIR(a,b) mkdir((a), (b))
00068 #define REMOVE(a) remove((a))
00069 #define MKSTEMP(a) mkstemp((a))
00070 #define DIR_SEPARATOR_CHAR '/'
00071 #define DIR_SEPARATOR_STR "/"
00072 #endif
00073 
00074 #define CACHE_META ".meta"
00075 #define CACHE_INDEX ".index"
00076 #define CACHE_EMPTY_ETAG "@cache@"
00077 
00078 #define NO_LM_EXPIRATION 24*3600 // 24 hours
00079 #define MAX_LM_EXPIRATION 48*3600 // Max expiration from LM
00080 
00081 // If using LM to find the expiration then take 10% and no more than
00082 // MAX_LM_EXPIRATION.
00083 #ifndef LM_EXPIRATION
00084 #define LM_EXPIRATION(t) (min((MAX_LM_EXPIRATION), static_cast<int>((t) / 10)))
00085 #endif
00086 
00087 const int CACHE_TABLE_SIZE = 1499;
00088 
00089 using namespace std;
00090 
00091 namespace libdap {
00092 
00096 int
00097 get_hash(const string &url)
00098 {
00099     int hash = 0;
00100 
00101     for (const char *ptr = url.c_str(); *ptr; ptr++)
00102         hash = (int)((hash * 3 + (*(unsigned char *)ptr)) % CACHE_TABLE_SIZE);
00103 
00104     return hash;
00105 }
00106 
00107 HTTPCacheTable::HTTPCacheTable(const string &cache_root, int block_size) :
00108         d_cache_root(cache_root),
00109         d_block_size(block_size),
00110         d_current_size(0),
00111         d_new_entries(0)
00112 {
00113         d_cache_index = cache_root + CACHE_INDEX;
00114         
00115         d_cache_table = new CacheEntries*[CACHE_TABLE_SIZE];
00116         
00117         // Initialize the cache table.
00118     for (int i = 0; i < CACHE_TABLE_SIZE; ++i)
00119         d_cache_table[i] = 0;
00120     
00121     cache_index_read();
00122 }
00123 
00127 static inline void
00128 delete_cache_entry(HTTPCacheTable::CacheEntry *e)
00129 {
00130     DBG2(cerr << "Deleting CacheEntry: " << e << endl);
00131     delete e;
00132 }
00133 
00134 HTTPCacheTable::~HTTPCacheTable() {
00135         for (int i = 0; i < CACHE_TABLE_SIZE; ++i) {
00136                 HTTPCacheTable::CacheEntries *cp = get_cache_table()[i];
00137                 if (cp) {
00138                         // delete each entry
00139                         for_each(cp->begin(), cp->end(), delete_cache_entry);
00140                         
00141                         // now delete the vector that held the entries
00142                         delete get_cache_table()[i];
00143                         get_cache_table()[i] = 0;
00144                 }
00145         }
00146         
00147         delete[] d_cache_table;
00148 }
00149 
00157 class DeleteExpired : public unary_function<HTTPCacheTable::CacheEntry *&, void> {
00158         time_t d_time;
00159         HTTPCacheTable &d_table;
00160 
00161 public:
00162         DeleteExpired(HTTPCacheTable &table, time_t t) :
00163                 d_time(t), d_table(table) {
00164                 if (!t)
00165                         d_time = time(0); // 0 == now
00166         } 
00167 
00168         void operator()(HTTPCacheTable::CacheEntry *&e) {
00169                 if (e && !e->readers && (e->freshness_lifetime
00170                                 < (e->corrected_initial_age + (d_time - e->response_time)))) {
00171                         DBG(cerr << "Deleting expired cache entry: " << e->url << endl);
00172                         d_table.remove_cache_entry(e);
00173                         delete e; e = 0;
00174                 }
00175         }
00176 };
00177 
00178 // @param time base deletes againt this time, defaults to 0 (now)
00179 void HTTPCacheTable::delete_expired_entries(time_t time) {
00180         // Walk through and delete all the expired entries.
00181         for (int cnt = 0; cnt < CACHE_TABLE_SIZE; cnt++) {
00182                 HTTPCacheTable::CacheEntries *slot = get_cache_table()[cnt];
00183                 if (slot) {
00184                         for_each(slot->begin(), slot->end(), DeleteExpired(*this, time));
00185                         slot->erase(remove(slot->begin(), slot->end(),
00186                                         static_cast<HTTPCacheTable::CacheEntry *>(0)), slot->end());
00187                 }
00188         }
00189 }
00190 
00197 class DeleteByHits : public unary_function<HTTPCacheTable::CacheEntry *&, void> {
00198         HTTPCacheTable &d_table;
00199         int d_hits;
00200 
00201 public:
00202         DeleteByHits(HTTPCacheTable &table, int hits) :
00203                 d_table(table), d_hits(hits) {
00204         }
00205 
00206         void operator()(HTTPCacheTable::CacheEntry *&e) {
00207                 if (e && !e->readers && e->hits <= d_hits) {
00208                         DBG(cerr << "Deleting cache entry: " << e->url << endl);
00209                         d_table.remove_cache_entry(e);
00210                         delete e; e = 0;
00211                 }
00212         }
00213 };
00214 
00215 void 
00216 HTTPCacheTable::delete_by_hits(int hits) {
00217     for (int cnt = 0; cnt < CACHE_TABLE_SIZE; cnt++) {
00218         if (get_cache_table()[cnt]) {
00219             HTTPCacheTable::CacheEntries *slot = get_cache_table()[cnt];
00220             for_each(slot->begin(), slot->end(), DeleteByHits(*this, hits));
00221             slot->erase(remove(slot->begin(), slot->end(),
00222                                static_cast<HTTPCacheTable::CacheEntry*>(0)),
00223                         slot->end());
00224 
00225         }
00226     }
00227 }
00228 
00233 class DeleteBySize : public unary_function<HTTPCacheTable::CacheEntry *&, void> {
00234         HTTPCacheTable &d_table;
00235         unsigned int d_size;
00236 
00237 public:
00238         DeleteBySize(HTTPCacheTable &table, unsigned int size) :
00239                 d_table(table), d_size(size) {
00240         }
00241 
00242         void operator()(HTTPCacheTable::CacheEntry *&e) {
00243                 if (e && !e->readers && e->size > d_size) {
00244                         DBG(cerr << "Deleting cache entry: " << e->url << endl);
00245                         d_table.remove_cache_entry(e);
00246                         delete e; e = 0;
00247                 }
00248         }
00249 };
00250 
00251 void HTTPCacheTable::delete_by_size(unsigned int size) {
00252     for (int cnt = 0; cnt < CACHE_TABLE_SIZE; cnt++) {
00253         if (get_cache_table()[cnt]) {
00254             HTTPCacheTable::CacheEntries *slot = get_cache_table()[cnt];
00255             for_each(slot->begin(), slot->end(), DeleteBySize(*this, size));
00256             slot->erase(remove(slot->begin(), slot->end(),
00257                                static_cast<HTTPCacheTable::CacheEntry*>(0)),
00258                         slot->end());
00259 
00260         }
00261     }
00262 }
00263 
00270 
00277 bool
00278 HTTPCacheTable::cache_index_delete()
00279 {
00280         d_new_entries = 0;
00281         
00282     return (REMOVE(d_cache_index.c_str()) == 0);
00283 }
00284 
00293 bool
00294 HTTPCacheTable::cache_index_read()
00295 {
00296     FILE *fp = fopen(d_cache_index.c_str(), "r");
00297     // If the cache index can't be opened that's OK; start with an empty
00298     // cache. 09/05/02 jhrg
00299     if (!fp) {
00300         return false;
00301     }
00302 
00303     char line[1024];
00304     while (!feof(fp) && fgets(line, 1024, fp)) {
00305         add_entry_to_cache_table(cache_index_parse_line(line));
00306         DBG2(cerr << line << endl);
00307     }
00308 
00309     int res = fclose(fp) ;
00310     if (res) {
00311         DBG(cerr << "HTTPCache::cache_index_read - Failed to close " << (void *)fp << endl);
00312     }
00313 
00314     d_new_entries = 0;
00315     
00316     return true;
00317 }
00318 
00326 HTTPCacheTable::CacheEntry *
00327 HTTPCacheTable::cache_index_parse_line(const char *line)
00328 {
00329     // Read the line and create the cache object
00330         HTTPCacheTable::CacheEntry *entry = new HTTPCacheTable::CacheEntry;
00331     istringstream iss(line);
00332     iss >> entry->url;
00333     iss >> entry->cachename;
00334 
00335     iss >> entry->etag;
00336     if (entry->etag == CACHE_EMPTY_ETAG)
00337         entry->etag = "";
00338 
00339     iss >> entry->lm;
00340     iss >> entry->expires;
00341     iss >> entry->size;
00342     iss >> entry->range; // range is not used. 10/02/02 jhrg
00343 
00344     iss >> entry->hash;
00345     iss >> entry->hits;
00346     iss >> entry->freshness_lifetime;
00347     iss >> entry->response_time;
00348     iss >> entry->corrected_initial_age;
00349 
00350     iss >> entry->must_revalidate;
00351 
00352     return entry;
00353 }
00354 
00357 class WriteOneCacheEntry :
00358         public unary_function<HTTPCacheTable::CacheEntry *, void>
00359 {
00360 
00361     FILE *d_fp;
00362 
00363 public:
00364     WriteOneCacheEntry(FILE *fp) : d_fp(fp)
00365     {}
00366 
00367     void operator()(HTTPCacheTable::CacheEntry *e)
00368     {
00369         if (e && fprintf(d_fp,
00370                          "%s %s %s %ld %ld %ld %c %d %d %ld %ld %ld %c\r\n",
00371                          e->url.c_str(),
00372                          e->cachename.c_str(),
00373                          e->etag == "" ? CACHE_EMPTY_ETAG : e->etag.c_str(),
00374                          (long)(e->lm),
00375                          (long)(e->expires),
00376                          e->size,
00377                          e->range ? '1' : '0', // not used. 10/02/02 jhrg
00378                          e->hash,
00379                          e->hits,
00380                          (long)(e->freshness_lifetime),
00381                          (long)(e->response_time),
00382                          (long)(e->corrected_initial_age),
00383                          e->must_revalidate ? '1' : '0') < 0)
00384             throw Error("Cache Index. Error writing cache index\n");
00385     }
00386 };
00387 
00397 void
00398 HTTPCacheTable::cache_index_write()
00399 {
00400     DBG(cerr << "Cache Index. Writing index " << d_cache_index << endl);
00401 
00402     // Open the file for writing.
00403     FILE * fp = NULL;
00404     if ((fp = fopen(d_cache_index.c_str(), "wb")) == NULL) {
00405         throw Error(string("Cache Index. Can't open `") + d_cache_index
00406                     + string("' for writing"));
00407     }
00408 
00409     // Walk through the list and write it out. The format is really
00410     // simple as we keep it all in ASCII.
00411 
00412     for (int cnt = 0; cnt < CACHE_TABLE_SIZE; cnt++) {
00413         HTTPCacheTable::CacheEntries *cp = get_cache_table()[cnt];
00414         if (cp)
00415             for_each(cp->begin(), cp->end(), WriteOneCacheEntry(fp));
00416     }
00417 
00418     /* Done writing */
00419     int res = fclose(fp);
00420     if (res) {
00421         DBG(cerr << "HTTPCache::cache_index_write - Failed to close "
00422             << (void *)fp << endl);
00423     }
00424 
00425     d_new_entries = 0;
00426 }
00427 
00429 
00442 string
00443 HTTPCacheTable::create_hash_directory(int hash)
00444 {
00445     struct stat stat_info;
00446     ostringstream path;
00447 
00448     path << d_cache_root << hash;
00449     string p = path.str();
00450 
00451     if (stat(p.c_str(), &stat_info) == -1) {
00452         DBG2(cerr << "Cache....... Create dir " << p << endl);
00453         if (MKDIR(p.c_str(), 0777) < 0) {
00454             DBG2(cerr << "Cache....... Can't create..." << endl);
00455             throw Error("Could not create cache slot to hold response! Check the write permissions on your disk cache directory. Cache root: " + d_cache_root + ".");
00456         }
00457     }
00458     else {
00459         DBG2(cerr << "Cache....... Directory " << p << " already exists"
00460              << endl);
00461     }
00462 
00463     return p;
00464 }
00465 
00480 void
00481 HTTPCacheTable::create_location(HTTPCacheTable::CacheEntry *entry)
00482 {
00483     string hash_dir = create_hash_directory(entry->hash);
00484 #ifdef WIN32
00485     hash_dir += "\\dodsXXXXXX";
00486 #else
00487     hash_dir += "/dodsXXXXXX"; // mkstemp uses six characters.
00488 #endif
00489 
00490     // mkstemp uses the storage passed to it; must be writable and local.
00491     char *templat = new char[hash_dir.size() + 1];
00492     strcpy(templat, hash_dir.c_str());
00493 
00494     // Open truncated for update. NB: mkstemp() returns a file descriptor.
00495     // man mkstemp says "... The file is opened with the O_EXCL flag,
00496     // guaranteeing that when mkstemp returns successfully we are the only
00497     // user." 09/19/02 jhrg
00498     int fd = MKSTEMP(templat); // fd mode is 666 or 600 (Unix)
00499     if (fd < 0) {
00500         delete[] templat; templat = 0;
00501         close(fd);
00502         throw Error("The HTTP Cache could not create a file to hold the response; it will not be cached.");
00503     }
00504 
00505     entry->cachename = templat;
00506     delete[] templat; templat = 0;
00507     close(fd);
00508 }
00509 
00510 
00512 static inline int
00513 entry_disk_space(int size, unsigned int block_size)
00514 {
00515     unsigned int num_of_blocks = (size + block_size) / block_size;
00516     
00517     DBG(cerr << "size: " << size << ", block_size: " << block_size
00518         << ", num_of_blocks: " << num_of_blocks << endl);
00519 
00520     return num_of_blocks * block_size;
00521 }
00522 
00526 
00532 void
00533 HTTPCacheTable::add_entry_to_cache_table(CacheEntry *entry)
00534 {
00535     int hash = entry->hash;
00536 
00537     if (!d_cache_table[hash])
00538         d_cache_table[hash] = new CacheEntries;
00539 
00540     d_cache_table[hash]->push_back(entry);
00541     
00542     DBG(cerr << "add_entry_to_cache_table, current_size: " << d_current_size
00543         << ", entry->size: " << entry->size << ", block size: " << d_block_size 
00544         << endl);
00545     
00546     d_current_size += entry_disk_space(entry->size, d_block_size);
00547 
00548     DBG(cerr << "add_entry_to_cache_table, current_size: " << d_current_size << endl);
00549     
00550     increment_new_entries();
00551 }
00552 
00556 HTTPCacheTable::CacheEntry *
00557 HTTPCacheTable::get_locked_entry_from_cache_table(const string &url) /*const*/
00558 {
00559     return get_locked_entry_from_cache_table(get_hash(url), url);
00560 }
00561 
00569 HTTPCacheTable::CacheEntry *
00570 HTTPCacheTable::get_locked_entry_from_cache_table(int hash, const string &url) /*const*/
00571 {
00572         DBG(cerr << "url: " << url << "; hash: " << hash << endl);
00573         DBG(cerr << "d_cache_table: " << hex << d_cache_table << dec << endl);
00574     if (d_cache_table[hash]) {
00575         CacheEntries *cp = d_cache_table[hash];
00576         for (CacheEntriesIter i = cp->begin(); i != cp->end(); ++i) {
00577             // Must test *i because perform_garbage_collection may have
00578             // removed this entry; the CacheEntry will then be null.
00579             if ((*i) && (*i)->url == url) {
00580                 (*i)->lock_read_response();     // Lock the response
00581                 return *i;
00582             }
00583         }
00584     }
00585 
00586     return 0;
00587 }
00588 
00595 HTTPCacheTable::CacheEntry *
00596 HTTPCacheTable::get_write_locked_entry_from_cache_table(const string &url)
00597 {
00598         int hash = get_hash(url);
00599     if (d_cache_table[hash]) {
00600         CacheEntries *cp = d_cache_table[hash];
00601         for (CacheEntriesIter i = cp->begin(); i != cp->end(); ++i) {
00602             // Must test *i because perform_garbage_collection may have
00603             // removed this entry; the CacheEntry will then be null.
00604             if ((*i) && (*i)->url == url) {
00605                 (*i)->lock_write_response();    // Lock the response
00606                 return *i;
00607             }
00608         }
00609     }
00610 
00611     return 0;
00612 }
00613 
00621 void
00622 HTTPCacheTable::remove_cache_entry(HTTPCacheTable::CacheEntry *entry)
00623 {
00624     // This should never happen; all calls to this method are protected by
00625     // the caller, hence the InternalErr.
00626     if (entry->readers)
00627         throw InternalErr(__FILE__, __LINE__, "Tried to delete a cache entry that is in use.");
00628 
00629     REMOVE(entry->cachename.c_str());
00630     REMOVE(string(entry->cachename + CACHE_META).c_str());
00631 
00632     DBG(cerr << "remove_cache_entry, current_size: " << get_current_size() << endl);
00633 
00634     unsigned int eds = entry_disk_space(entry->size, get_block_size());
00635     set_current_size((eds > get_current_size()) ? 0 : get_current_size() - eds);
00636     
00637     DBG(cerr << "remove_cache_entry, current_size: " << get_current_size() << endl);
00638 }
00639 
00642 class DeleteCacheEntry: public unary_function<HTTPCacheTable::CacheEntry *&, void>
00643 {
00644     string d_url;
00645     HTTPCacheTable *d_cache_table;
00646 
00647 public:
00648     DeleteCacheEntry(HTTPCacheTable *c, const string &url)
00649             : d_url(url), d_cache_table(c)
00650     {}
00651 
00652     void operator()(HTTPCacheTable::CacheEntry *&e)
00653     {
00654         if (e && e->url == d_url) {
00655                 e->lock_write_response();
00656             d_cache_table->remove_cache_entry(e);
00657                 e->unlock_write_response();
00658             delete e; e = 0;
00659         }
00660     }
00661 };
00662 
00669 void
00670 HTTPCacheTable::remove_entry_from_cache_table(const string &url)
00671 {
00672     int hash = get_hash(url);
00673     if (d_cache_table[hash]) {
00674         CacheEntries *cp = d_cache_table[hash];
00675         for_each(cp->begin(), cp->end(), DeleteCacheEntry(this, url));
00676         cp->erase(remove(cp->begin(), cp->end(), static_cast<HTTPCacheTable::CacheEntry*>(0)),
00677                   cp->end());
00678     }
00679 }
00680 
00683 class DeleteUnlockedCacheEntry :
00684         public unary_function<HTTPCacheTable::CacheEntry *&, void> {
00685         HTTPCacheTable &d_table;
00686 
00687 public:
00688         DeleteUnlockedCacheEntry(HTTPCacheTable &t) :
00689                 d_table(t) {
00690         }
00691         void operator()(HTTPCacheTable::CacheEntry *&e) {
00692                 if (e) {
00693                         d_table.remove_cache_entry(e);
00694                         delete e; e = 0;
00695                 }
00696         }
00697 };
00698 
00699 void HTTPCacheTable::delete_all_entries() {
00700         // Walk through the cache table and, for every entry in the cache, delete
00701         // it on disk and in the cache table.
00702         for (int cnt = 0; cnt < CACHE_TABLE_SIZE; cnt++) {
00703                 HTTPCacheTable::CacheEntries *slot = get_cache_table()[cnt];
00704                 if (slot) {
00705                         for_each(slot->begin(), slot->end(), DeleteUnlockedCacheEntry(*this));
00706                         slot->erase(remove(slot->begin(), slot->end(), static_cast<HTTPCacheTable::CacheEntry *>(0)), 
00707                                             slot->end());
00708                 }
00709         }
00710         
00711         cache_index_delete();
00712 }
00713 
00727 void
00728 HTTPCacheTable::calculate_time(HTTPCacheTable::CacheEntry *entry, int default_expiration, time_t request_time)
00729 {
00730     entry->response_time = time(NULL);
00731     time_t apparent_age = max(0, static_cast<int>(entry->response_time - entry->date));
00732     time_t corrected_received_age = max(apparent_age, entry->age);
00733     time_t response_delay = entry->response_time - request_time;
00734     entry->corrected_initial_age = corrected_received_age + response_delay;
00735 
00736     // Estimate an expires time using the max-age and expires time. If we
00737     // don't have an explicit expires time then set it to 10% of the LM date
00738     // (although max 24 h). If no LM date is available then use 24 hours.
00739     time_t freshness_lifetime = entry->max_age;
00740     if (freshness_lifetime < 0) {
00741         if (entry->expires < 0) {
00742             if (entry->lm < 0) {
00743                 freshness_lifetime = default_expiration;
00744             }
00745             else {
00746                 freshness_lifetime = LM_EXPIRATION(entry->date - entry->lm);
00747             }
00748         }
00749         else
00750             freshness_lifetime = entry->expires - entry->date;
00751     }
00752 
00753     entry->freshness_lifetime = max(0, static_cast<int>(freshness_lifetime));
00754 
00755     DBG2(cerr << "Cache....... Received Age " << entry->age
00756          << ", corrected " << entry->corrected_initial_age
00757          << ", freshness lifetime " << entry->freshness_lifetime << endl);
00758 }
00759 
00771 void HTTPCacheTable::parse_headers(HTTPCacheTable::CacheEntry *entry,
00772                 unsigned long max_entry_size, const vector<string> &headers) {
00773         vector<string>::const_iterator i;
00774         for (i = headers.begin(); i != headers.end(); ++i) {
00775                 // skip a blank header.
00776                 if ((*i).empty())
00777                         continue;
00778 
00779                 string::size_type colon = (*i).find(':');
00780 
00781                 // skip a header with no colon in it.
00782                 if (colon == string::npos)
00783                         continue;
00784 
00785                 string header = (*i).substr(0, (*i).find(':'));
00786                 string value = (*i).substr((*i).find(": ") + 2);
00787                 DBG2(cerr << "Header: " << header << endl);DBG2(cerr << "Value: " << value << endl);
00788 
00789                 if (header == "ETag") {
00790                         entry->etag = value;
00791                 } else if (header == "Last-Modified") {
00792                         entry->lm = parse_time(value.c_str());
00793                 } else if (header == "Expires") {
00794                         entry->expires = parse_time(value.c_str());
00795                 } else if (header == "Date") {
00796                         entry->date = parse_time(value.c_str());
00797                 } else if (header == "Age") {
00798                         entry->age = parse_time(value.c_str());
00799                 } else if (header == "Content-Length") {
00800                         unsigned long clength = strtoul(value.c_str(), 0, 0);
00801                         if (clength > max_entry_size)
00802                                 entry->set_no_cache(true);
00803                 } else if (header == "Cache-Control") {
00804                         // Ignored Cache-Control values: public, private, no-transform,
00805                         // proxy-revalidate, s-max-age. These are used by shared caches.
00806                         // See section 14.9 of RFC 2612. 10/02/02 jhrg
00807                         if (value == "no-cache" || value == "no-store")
00808                                 // Note that we *can* store a 'no-store' response in volatile
00809                                 // memory according to RFC 2616 (section 14.9.2) but those
00810                                 // will be rare coming from DAP servers. 10/02/02 jhrg
00811                                 entry->set_no_cache(true);
00812                         else if (value == "must-revalidate")
00813                                 entry->must_revalidate = true;
00814                         else if (value.find("max-age") != string::npos) {
00815                                 string max_age = value.substr(value.find("=" + 1));
00816                                 entry->max_age = parse_time(max_age.c_str());
00817                         }
00818                 }
00819         }
00820 }
00821 
00823 
00824 // @TODO Change name to record locked response
00825 void HTTPCacheTable::bind_entry_to_data(HTTPCacheTable::CacheEntry *entry, FILE *body) {
00826         entry->hits++;  // Mark hit
00827     d_locked_entries[body] = entry; // record lock, see release_cached_r...
00828 }
00829 
00830 void HTTPCacheTable::uncouple_entry_from_data(FILE *body) {
00831         HTTPCacheTable::CacheEntry *entry = d_locked_entries[body];
00832     if (!entry)
00833         throw InternalErr("There is no cache entry for the response given.");
00834 
00835     d_locked_entries.erase(body);
00836     entry->unlock_read_response();
00837 
00838     if (entry->readers < 0)
00839         throw InternalErr("An unlocked entry was released");
00840 }
00841 
00842 bool HTTPCacheTable::is_locked_read_responses() {
00843         return !d_locked_entries.empty();
00844 }
00845 
00846 } // namespace libdap