X-Git-Url: https://code.citadel.org/?a=blobdiff_plain;f=citadel%2Fdatabase_sleepycat.c;h=0573ae5de032cfce2ac565ba0e96768a3459caf5;hb=11219dbc3e638e7ee47feffbbb7d63588d7dd77f;hp=dc77215e7a4e8e6f1ed6954db26ed4509ca06fc5;hpb=425f004d7eab12dcddb0a10771b3fbd2fb1a6db8;p=citadel.git

diff --git a/citadel/database_sleepycat.c b/citadel/database_sleepycat.c
index dc77215e7..0573ae5de 100644
--- a/citadel/database_sleepycat.c
+++ b/citadel/database_sleepycat.c
@@ -1,109 +1,406 @@
 /*
  * $Id$
  *
- * Sleepycat (Berkeley) DB driver for Citadel/UX
+ * Sleepycat (Berkeley) DB driver for Citadel
  *
  */
 
+/*****************************************************************************
+       Tunable configuration parameters for the Sleepycat DB back end
+ *****************************************************************************/
+
+/* Citadel will checkpoint the db at the end of every session, but only if
+ * the specified number of kilobytes has been written, or if the specified
+ * number of minutes has passed, since the last checkpoint.
+ */
+#define MAX_CHECKPOINT_KBYTES	256
+#define MAX_CHECKPOINT_MINUTES	15
+
+/*****************************************************************************/
+
 #include "sysdep.h"
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
-#include <time.h>
 #include <ctype.h>
 #include <string.h>
 #include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+
+#ifdef HAVE_DB_H
 #include <db.h>
+#elif defined(HAVE_DB4_DB_H)
+#include <db4/db.h>
+#else
+#error Neither <db.h> nor <db4/db.h> was found by configure. Install db4-devel.
+#endif
+
+
+#if DB_VERSION_MAJOR < 4 || DB_VERSION_MINOR < 1
+#error Citadel requires Berkeley DB v4.1 or newer.  Please upgrade.
+#endif
+
+
+#include <pthread.h>
 #include "citadel.h"
 #include "server.h"
+#include "serv_extensions.h"
 #include "citserver.h"
 #include "database.h"
+#include "msgbase.h"
 #include "sysdep_decls.h"
+#include "config.h"
+
+static DB *dbp[MAXCDB];		/* One DB handle for each Citadel database */
+static DB_ENV *dbenv;		/* The DB environment (global) */
+
+struct cdbtsd {			/* Thread-specific DB stuff */
+	DB_TXN *tid;		/* Transaction handle */
+	DBC *cursors[MAXCDB];	/* Cursors, for traversals... */
+};
+
+#ifdef HAVE_ZLIB
+#include <zlib.h>
+#endif
+
+static pthread_key_t tsdkey;
+
+#define MYCURSORS	(((struct cdbtsd*)pthread_getspecific(tsdkey))->cursors)
+#define MYTID		(((struct cdbtsd*)pthread_getspecific(tsdkey))->tid)
+
+/* just a little helper function */
+static void txabort(DB_TXN * tid)
+{
+	int ret;
+
+	ret = tid->abort(tid);
+
+	if (ret) {
+		lprintf(CTDL_EMERG, "cdb_*: txn_abort: %s\n",
+			db_strerror(ret));
+		abort();
+	}
+}
+
+/* this one is even more helpful than the last. */
+static void txcommit(DB_TXN * tid)
+{
+	int ret;
+
+	ret = tid->commit(tid, 0);
+
+	if (ret) {
+		lprintf(CTDL_EMERG, "cdb_*: txn_commit: %s\n",
+			db_strerror(ret));
+		abort();
+	}
+}
+
+/* are you sensing a pattern yet? */
+static void txbegin(DB_TXN ** tid)
+{
+	int ret;
+
+	ret = dbenv->txn_begin(dbenv, NULL, tid, 0);
+
+	if (ret) {
+		lprintf(CTDL_EMERG, "cdb_*: txn_begin: %s\n",
+			db_strerror(ret));
+		abort();
+	}
+}
+
+static void dbpanic(DB_ENV * env, int errval)
+{
+	lprintf(CTDL_EMERG, "cdb_*: Berkeley DB panic: %d\n", errval);
+}
+
+static void cclose(DBC * cursor)
+{
+	int ret;
+
+	if ((ret = cursor->c_close(cursor))) {
+		lprintf(CTDL_EMERG, "cdb_*: c_close: %s\n",
+			db_strerror(ret));
+		abort();
+	}
+}
+
+static void bailIfCursor(DBC ** cursors, const char *msg)
+{
+	int i;
+
+	for (i = 0; i < MAXCDB; i++)
+		if (cursors[i] != NULL) {
+			lprintf(CTDL_EMERG,
+				"cdb_*: cursor still in progress on cdb %d: %s\n",
+				i, msg);
+			abort();
+		}
+}
+
+static void check_handles(void *arg)
+{
+	if (arg != NULL) {
+		struct cdbtsd *tsd = (struct cdbtsd *) arg;
 
+		bailIfCursor(tsd->cursors, "in check_handles");
+
+		if (tsd->tid != NULL) {
+			lprintf(CTDL_EMERG,
+				"cdb_*: transaction still in progress!");
+			abort();
+		}
+	}
+}
+
+static void dest_tsd(void *arg)
+{
+	if (arg != NULL) {
+		check_handles(arg);
+		free(arg);
+	}
+}
 
 /*
- * This array holds one DB handle for each Citadel database.
+ * Ensure that we have a key for thread-specific data.  We don't
+ * put anything in here that Citadel cares about; this is just database
+ * related stuff like cursors and transactions.
+ *
+ * This should be called immediately after startup by any thread which wants
+ * to use database calls, except for whatever thread calls open_databases.
  */
-DB *dbp[MAXCDB];
+void cdb_allocate_tsd(void)
+{
+	struct cdbtsd *tsd;
+
+	if (pthread_getspecific(tsdkey) != NULL)
+		return;
+
+	tsd = malloc(sizeof(struct cdbtsd));
+
+	tsd->tid = NULL;
+
+	memset(tsd->cursors, 0, sizeof tsd->cursors);
+	pthread_setspecific(tsdkey, tsd);
+}
 
-DB_ENV *dbenv;
+void cdb_free_tsd(void)
+{
+	dest_tsd(pthread_getspecific(tsdkey));
+	pthread_setspecific(tsdkey, NULL);
+}
+
+void cdb_check_handles(void)
+{
+	check_handles(pthread_getspecific(tsdkey));
+}
 
-DBC *cursorz[999];	/* FIXME !! */
-#define MYCURSOR cursorz[CC->cs_pid]
 
 /*
  * Reclaim unused space in the databases.  We need to do each one of
  * these discretely, rather than in a loop.
+ *
+ * This is a stub function in the Sleepycat DB backend, because there is no
+ * such API call available.
  */
 void defrag_databases(void)
 {
-	/* FIXME ... do we even need this?  If not, we'll just keep it as
-	 * a stub function to keep the API consistent.
-	 */
+	/* do nothing */
 }
 
 
+/*
+ * Cull the database logs
+ */
+static void cdb_cull_logs(void)
+{
+	u_int32_t flags;
+	int ret;
+	char **file, **list;
+	char errmsg[SIZ];
+
+	flags = DB_ARCH_ABS;
+
+	/* Get the list of names. */
+	if ((ret = dbenv->log_archive(dbenv, &list, flags)) != 0) {
+		lprintf(CTDL_ERR, "cdb_cull_logs: %s\n", db_strerror(ret));
+		return;
+	}
+
+	/* Print the list of names. */
+	if (list != NULL) {
+		for (file = list; *file != NULL; ++file) {
+			lprintf(CTDL_DEBUG, "Deleting log: %s\n", *file);
+			ret = unlink(*file);
+			if (ret != 0) {
+				snprintf(errmsg, sizeof(errmsg),
+					 " ** ERROR **\n \n \n "
+					 "Citadel was unable to delete the "
+					 "database log file '%s' because of the "
+					 "following error:\n \n %s\n \n"
+					 " This log file is no longer in use "
+					 "and may be safely deleted.\n",
+					 *file, strerror(errno));
+				aide_message(errmsg, "Database Warning Message");
+			}
+		}
+		free(list);
+	}
+}
+
+/*
+ * Manually initiate log file cull.
+ */
+void cmd_cull(char *argbuf) {
+	if (CtdlAccessCheck(ac_internal)) return;
+	cdb_cull_logs();
+	cprintf("%d Database log file cull completed.\n", CIT_OK);
+}
+
+
+/*
+ * Request a checkpoint of the database.
+ */
+static void cdb_checkpoint(void)
+{
+	int ret;
+	static time_t last_run = 0L;
+
+	/* Only do a checkpoint once per minute. */
+	if ((time(NULL) - last_run) < 60L) {
+		return;
+	}
+	last_run = time(NULL);
+
+	lprintf(CTDL_DEBUG, "-- db checkpoint --\n");
+	ret = dbenv->txn_checkpoint(dbenv,
+				    MAX_CHECKPOINT_KBYTES,
+				    MAX_CHECKPOINT_MINUTES, 0);
+
+	if (ret != 0) {
+		lprintf(CTDL_EMERG, "cdb_checkpoint: txn_checkpoint: %s\n",
+			db_strerror(ret));
+		abort();
+	}
+
+	/* After a successful checkpoint, we can cull the unused logs */
+	if (config.c_auto_cull) {
+		cdb_cull_logs();
+	}
+}
+
+
+/*
+ * Main loop for the checkpoint thread.
+ */
+void *checkpoint_thread(void *arg) {
+	struct CitContext checkpointCC;
+
+	lprintf(CTDL_DEBUG, "checkpoint_thread() initializing\n");
+
+	memset(&checkpointCC, 0, sizeof(struct CitContext));
+	checkpointCC.internal_pgm = 1;
+	checkpointCC.cs_pid = 0;
+	pthread_setspecific(MyConKey, (void *)&checkpointCC );
+
+	cdb_allocate_tsd();
+
+	while (!time_to_die) {
+		cdb_checkpoint();
+		sleep(1);
+	}
+
+	lprintf(CTDL_DEBUG, "checkpoint_thread() exiting\n");
+	pthread_exit(NULL);
+}
+
 /*
  * Open the various databases we'll be using.  Any database which
- * does not exist should be created.  Note that we don't need an S_DATABASE
- * critical section here, because there aren't any active threads manipulating
- * the database yet -- and besides, it causes problems on BSDI.
+ * does not exist should be created.  Note that we don't need a
+ * critical section here, because there aren't any active threads
+ * manipulating the database yet.
  */
 void open_databases(void)
 {
 	int ret;
 	int i;
-	char dbfilename[256];
-
-        /*
-         * Silently try to create the database subdirectory.  If it's
-         * already there, no problem.
-         */
-        system("exec mkdir data 2>/dev/null");
+	char dbfilename[SIZ];
+	u_int32_t flags = 0;
+	DIR *dp;
+	struct dirent *d;
+	char filename[PATH_MAX];
+
+	lprintf(CTDL_DEBUG, "cdb_*: open_databases() starting\n");
+	lprintf(CTDL_DEBUG, "Compiled db: %s\n", DB_VERSION_STRING);
+	lprintf(CTDL_INFO, "  Linked db: %s\n",
+		db_version(NULL, NULL, NULL));
+#ifdef HAVE_ZLIB
+	lprintf(CTDL_INFO, "Linked zlib: %s\n", zlibVersion());
+#endif
+
+	/*
+	 * Silently try to create the database subdirectory.  If it's
+	 * already there, no problem.
+	 */
+	mkdir(ctdl_data_dir, 0700);
+	chmod(ctdl_data_dir, 0700);
+	chown(ctdl_data_dir, CTDLUID, (-1));
 
-	lprintf(9, "Setting up DB environment\n");
+	lprintf(CTDL_DEBUG, "cdb_*: Setting up DB environment\n");
+	db_env_set_func_yield(sched_yield);
 	ret = db_env_create(&dbenv, 0);
 	if (ret) {
-		lprintf(1, "db_env_create: %s\n", db_strerror(ret));
+		lprintf(CTDL_EMERG, "cdb_*: db_env_create: %s\n",
+			db_strerror(ret));
 		exit(ret);
 	}
-	dbenv->set_errfile(dbenv, stderr);  /* FIXME */
 	dbenv->set_errpfx(dbenv, "citserver");
+	dbenv->set_paniccall(dbenv, dbpanic);
 
-        /*
-         * We want to specify the shared memory buffer pool cachesize,
-         * but everything else is the default.
-         */
-        ret = dbenv->set_cachesize(dbenv, 0, 64 * 1024, 0);
+	/*
+	 * We want to specify the shared memory buffer pool cachesize,
+	 * but everything else is the default.
+	 */
+	ret = dbenv->set_cachesize(dbenv, 0, 64 * 1024, 0);
 	if (ret) {
-		lprintf(1, "set_cachesize: %s\n", db_strerror(ret));
-                dbenv->close(dbenv, 0);
-                exit(ret);
-        }
-
-        /*
-         * We have multiple processes reading/writing these files, so
-         * we need concurrency control and a shared buffer pool, but
-         * not logging or transactions.
-         */
-        /* (void)dbenv->set_data_dir(dbenv, "/database/files"); */
-        ret = dbenv->open(dbenv, "./data",
-        	( DB_CREATE | DB_INIT_MPOOL ),
-		0);
+		lprintf(CTDL_EMERG, "cdb_*: set_cachesize: %s\n",
+			db_strerror(ret));
+		dbenv->close(dbenv, 0);
+		exit(ret);
+	}
+
+	if ((ret = dbenv->set_lk_detect(dbenv, DB_LOCK_DEFAULT))) {
+		lprintf(CTDL_EMERG, "cdb_*: set_lk_detect: %s\n",
+			db_strerror(ret));
+		dbenv->close(dbenv, 0);
+		exit(ret);
+	}
+
+	flags =
+	    DB_CREATE | DB_RECOVER | DB_INIT_MPOOL | DB_PRIVATE |
+	    DB_INIT_TXN | DB_INIT_LOCK | DB_THREAD;
+	lprintf(CTDL_DEBUG, "dbenv->open(dbenv, %s, %d, 0)\n", ctdl_data_dir,
+		flags);
+	ret = dbenv->open(dbenv, ctdl_data_dir, flags, 0);
 	if (ret) {
-		lprintf(1, "dbenv->open: %s\n", db_strerror(ret));
-                dbenv->close(dbenv, 0);
-                exit(ret);
-        }
+		lprintf(CTDL_DEBUG, "cdb_*: dbenv->open: %s\n",
+			db_strerror(ret));
+		dbenv->close(dbenv, 0);
+		exit(ret);
+	}
 
-	lprintf(7, "Starting up DB\n");
+	lprintf(CTDL_INFO, "cdb_*: Starting up DB\n");
 
 	for (i = 0; i < MAXCDB; ++i) {
 
 		/* Create a database handle */
 		ret = db_create(&dbp[i], dbenv, 0);
 		if (ret) {
-			lprintf(1, "db_create: %s\n", db_strerror(ret));
+			lprintf(CTDL_DEBUG, "cdb_*: db_create: %s\n",
+				db_strerror(ret));
 			exit(ret);
 		}
 
@@ -111,26 +408,54 @@ void open_databases(void)
 		/* Arbitrary names for our tables -- we reference them by
 		 * number, so we don't have string names for them.
 		 */
-		sprintf(dbfilename, "cdb.%02x", i);
+		snprintf(dbfilename, sizeof dbfilename, "cdb.%02x", i);
 
 		ret = dbp[i]->open(dbp[i],
-				dbfilename,
-				NULL,
-				DB_BTREE,
-				DB_CREATE,
-				0600);
+				   NULL,
+				   dbfilename,
+				   NULL,
+				   DB_BTREE,
+				   DB_CREATE | DB_AUTO_COMMIT | DB_THREAD,
+				   0600);
 		if (ret) {
-			lprintf(1, "db_open[%d]: %s\n", i, db_strerror(ret));
+			lprintf(CTDL_EMERG, "cdb_*: db_open[%d]: %s\n", i,
+				db_strerror(ret));
 			exit(ret);
 		}
+	}
+
+	if ((ret = pthread_key_create(&tsdkey, dest_tsd))) {
+		lprintf(CTDL_EMERG, "cdb_*: pthread_key_create: %s\n",
+			strerror(ret));
+		exit(1);
+	}
+
+	cdb_allocate_tsd();
 
+	/* Now make sure we own all the files, because in a few milliseconds
+	 * we're going to drop root privs.
+	 */
+	dp = opendir(ctdl_data_dir);
+	if (dp != NULL) {
+		while (d = readdir(dp), d != NULL) {
+			if (d->d_name[0] != '.') {
+				snprintf(filename, sizeof filename,
+					 "%s/%s", ctdl_data_dir, d->d_name);
+				chmod(filename, 0600);
+				chown(filename, CTDLUID, (-1));
+			}
+		}
+		closedir(dp);
 	}
 
+	lprintf(CTDL_DEBUG, "cdb_*: open_databases() finished\n");
+
+	CtdlRegisterProtoHook(cmd_cull, "CULL", "Cull database logs");
 }
 
 
 /*
- * Close all of the gdbm database files we've opened.  This can be done
+ * Close all of the db database files we've opened.  This can be done
  * in a loop, since it's just a bunch of closes.
  */
 void close_databases(void)
@@ -138,42 +463,97 @@ void close_databases(void)
 	int a;
 	int ret;
 
-	begin_critical_section(S_DATABASE);
+	cdb_free_tsd();
+
+	if ((ret = dbenv->txn_checkpoint(dbenv, 0, 0, 0))) {
+		lprintf(CTDL_EMERG,
+			"cdb_*: txn_checkpoint: %s\n", db_strerror(ret));
+	}
+
 	for (a = 0; a < MAXCDB; ++a) {
-		lprintf(7, "Closing database %d\n", a);
+		lprintf(CTDL_INFO, "cdb_*: Closing database %d\n", a);
 		ret = dbp[a]->close(dbp[a], 0);
 		if (ret) {
-			lprintf(1, "db_close: %s\n", db_strerror(ret));
+			lprintf(CTDL_EMERG,
+				"cdb_*: db_close: %s\n", db_strerror(ret));
 		}
-		
-	}
-
 
+	}
 
-        /* Close the handle. */
-        ret = dbenv->close(dbenv, 0);
+	/* Close the handle. */
+	ret = dbenv->close(dbenv, 0);
 	if (ret) {
-                lprintf(1, "DBENV->close: %s\n", db_strerror(ret));
-        }
+		lprintf(CTDL_EMERG,
+			"cdb_*: DBENV->close: %s\n", db_strerror(ret));
+	}
+}
+
 
+/*
+ * Compression functions only used if we have zlib
+ */
+#ifdef HAVE_ZLIB
 
-	end_critical_section(S_DATABASE);
+void cdb_decompress_if_necessary(struct cdbdata *cdb)
+{
+	static int magic = COMPRESS_MAGIC;
+	struct CtdlCompressHeader zheader;
+	char *uncompressed_data;
+	char *compressed_data;
+	uLongf destLen, sourceLen;
+
+	if (cdb == NULL)
+		return;
+	if (cdb->ptr == NULL)
+		return;
+	if (memcmp(cdb->ptr, &magic, sizeof(magic)))
+		return;
+
+	/* At this point we know we're looking at a compressed item. */
+	memcpy(&zheader, cdb->ptr, sizeof(struct CtdlCompressHeader));
+
+	compressed_data = cdb->ptr;
+	compressed_data += sizeof(struct CtdlCompressHeader);
+
+	sourceLen = (uLongf) zheader.compressed_len;
+	destLen = (uLongf) zheader.uncompressed_len;
+	uncompressed_data = malloc(zheader.uncompressed_len);
+
+	if (uncompress((Bytef *) uncompressed_data,
+		       (uLongf *) & destLen,
+		       (const Bytef *) compressed_data,
+		       (uLong) sourceLen) != Z_OK) {
+		lprintf(CTDL_EMERG, "uncompress() error\n");
+		abort();
+	}
 
+	free(cdb->ptr);
+	cdb->len = (size_t) destLen;
+	cdb->ptr = uncompressed_data;
 }
 
+#endif				/* HAVE_ZLIB */
+
 
 /*
  * Store a piece of data.  Returns 0 if the operation was successful.  If a
  * key already exists it should be overwritten.
  */
-int cdb_store(int cdb,
-	      void *ckey, int ckeylen,
-	      void *cdata, int cdatalen)
+int cdb_store(int cdb, void *ckey, int ckeylen, void *cdata, int cdatalen)
 {
 
 	DBT dkey, ddata;
+	DB_TXN *tid;
 	int ret;
 
+#ifdef HAVE_ZLIB
+	struct CtdlCompressHeader zheader;
+	char *compressed_data = NULL;
+	int compressing = 0;
+	size_t buffer_len;
+	uLongf destLen;
+#endif
+
 	memset(&dkey, 0, sizeof(DBT));
 	memset(&ddata, 0, sizeof(DBT));
 	dkey.size = ckeylen;
@@ -181,21 +561,79 @@ int cdb_store(int cdb,
 	ddata.size = cdatalen;
 	ddata.data = cdata;
 
-	begin_critical_section(S_DATABASE);
-	lprintf(9, "cdb_store(%d) ...\n", cdb);
-	ret = dbp[cdb]->put(dbp[cdb],		/* db */
-				NULL,		/* transaction ID (hmm...) */
-				&dkey,		/* key */
-				&ddata,		/* data */
-				0);		/* flags */
-	end_critical_section(S_DATABASE);
-	lprintf(9, "...put (  to file %d) returned %3d (%d bytes)\n",
-		cdb, ret, ddata.size);
-	if (ret) {
-		lprintf(1, "cdb_store: %s\n", db_strerror(ret));
-		return (-1);
+#ifdef HAVE_ZLIB
+	/* Only compress Visit records.  Everything else is uncompressed. */
+	if (cdb == CDB_VISIT) {
+		compressing = 1;
+		zheader.magic = COMPRESS_MAGIC;
+		zheader.uncompressed_len = cdatalen;
+		buffer_len = ((cdatalen * 101) / 100) + 100
+		    + sizeof(struct CtdlCompressHeader);
+		destLen = (uLongf) buffer_len;
+		compressed_data = malloc(buffer_len);
+		if (compress2((Bytef *) (compressed_data +
+					 sizeof(struct
+						CtdlCompressHeader)),
+			      &destLen, (Bytef *) cdata, (uLongf) cdatalen,
+			      1) != Z_OK) {
+			lprintf(CTDL_EMERG, "compress2() error\n");
+			abort();
+		}
+		zheader.compressed_len = (size_t) destLen;
+		memcpy(compressed_data, &zheader,
+		       sizeof(struct CtdlCompressHeader));
+		ddata.size = (size_t) (sizeof(struct CtdlCompressHeader) +
+				       zheader.compressed_len);
+		ddata.data = compressed_data;
+	}
+#endif
+
+	if (MYTID != NULL) {
+		ret = dbp[cdb]->put(dbp[cdb],	/* db */
+				    MYTID,	/* transaction ID */
+				    &dkey,	/* key */
+				    &ddata,	/* data */
+				    0);	/* flags */
+		if (ret) {
+			lprintf(CTDL_EMERG, "cdb_store(%d): %s\n", cdb,
+				db_strerror(ret));
+			abort();
+		}
+#ifdef HAVE_ZLIB
+		if (compressing)
+			free(compressed_data);
+#endif
+		return ret;
+
+	} else {
+		bailIfCursor(MYCURSORS,
+			     "attempt to write during r/o cursor");
+
+	      retry:
+		txbegin(&tid);
+
+		if ((ret = dbp[cdb]->put(dbp[cdb],	/* db */
+					 tid,	/* transaction ID */
+					 &dkey,	/* key */
+					 &ddata,	/* data */
+					 0))) {	/* flags */
+			if (ret == DB_LOCK_DEADLOCK) {
+				txabort(tid);
+				goto retry;
+			} else {
+				lprintf(CTDL_EMERG, "cdb_store(%d): %s\n",
+					cdb, db_strerror(ret));
+				abort();
+			}
+		} else {
+			txcommit(tid);
+#ifdef HAVE_ZLIB
+			if (compressing)
+				free(compressed_data);
+#endif
+			return ret;
+		}
 	}
-	return (0);
 }
 
 
@@ -206,21 +644,64 @@ int cdb_delete(int cdb, void *key, int keylen)
 {
 
 	DBT dkey;
+	DB_TXN *tid;
 	int ret;
 
+	memset(&dkey, 0, sizeof dkey);
 	dkey.size = keylen;
 	dkey.data = key;
 
-	begin_critical_section(S_DATABASE);
-	lprintf(9, "cdb_delete(%d) ...\n", cdb);
-	ret = dbp[cdb]->del(dbp[cdb], NULL, &dkey, 0);
-	lprintf(9, "cdb_delete returned %d\n", ret);
-	end_critical_section(S_DATABASE);
-	return (ret);
-
+	if (MYTID != NULL) {
+		ret = dbp[cdb]->del(dbp[cdb], MYTID, &dkey, 0);
+		if (ret) {
+			lprintf(CTDL_EMERG, "cdb_delete(%d): %s\n", cdb,
+				db_strerror(ret));
+			if (ret != DB_NOTFOUND)
+				abort();
+		}
+	} else {
+		bailIfCursor(MYCURSORS,
+			     "attempt to delete during r/o cursor");
+
+	      retry:
+		txbegin(&tid);
+
+		if ((ret = dbp[cdb]->del(dbp[cdb], tid, &dkey, 0))
+		    && ret != DB_NOTFOUND) {
+			if (ret == DB_LOCK_DEADLOCK) {
+				txabort(tid);
+				goto retry;
+			} else {
+				lprintf(CTDL_EMERG, "cdb_delete(%d): %s\n",
+					cdb, db_strerror(ret));
+				abort();
+			}
+		} else {
+			txcommit(tid);
+		}
+	}
+	return ret;
 }
 
+static DBC *localcursor(int cdb)
+{
+	int ret;
+	DBC *curs;
+
+	if (MYCURSORS[cdb] == NULL)
+		ret = dbp[cdb]->cursor(dbp[cdb], MYTID, &curs, 0);
+	else
+		ret =
+		    MYCURSORS[cdb]->c_dup(MYCURSORS[cdb], &curs,
+					  DB_POSITION);
 
+	if (ret) {
+		lprintf(CTDL_EMERG, "localcursor: %s\n", db_strerror(ret));
+		abort();
+	}
+
+	return curs;
+}
 
 
 /*
@@ -236,57 +717,104 @@ struct cdbdata *cdb_fetch(int cdb, void *key, int keylen)
 	int ret;
 
 	memset(&dkey, 0, sizeof(DBT));
-	memset(&dret, 0, sizeof(DBT));
 	dkey.size = keylen;
 	dkey.data = key;
-	dret.flags = DB_DBT_MALLOC;
-
-	begin_critical_section(S_DATABASE);
-	lprintf(9, "cdb_fetch(%d) ...\n", cdb);
-	ret = dbp[cdb]->get(dbp[cdb], NULL, &dkey, &dret, 0);
-	end_critical_section(S_DATABASE);
-	lprintf(9, "get (from file %d) returned %3d (%d bytes)\n",
-		cdb, ret, dret.size);
+
+	if (MYTID != NULL) {
+		memset(&dret, 0, sizeof(DBT));
+		dret.flags = DB_DBT_MALLOC;
+		ret = dbp[cdb]->get(dbp[cdb], MYTID, &dkey, &dret, 0);
+	} else {
+		DBC *curs;
+
+		do {
+			memset(&dret, 0, sizeof(DBT));
+			dret.flags = DB_DBT_MALLOC;
+
+			curs = localcursor(cdb);
+
+			ret = curs->c_get(curs, &dkey, &dret, DB_SET);
+			cclose(curs);
+		}
+		while (ret == DB_LOCK_DEADLOCK);
+
+	}
+
 	if ((ret != 0) && (ret != DB_NOTFOUND)) {
-		lprintf(1, "cdb_fetch: %s\n", db_strerror(ret));
+		lprintf(CTDL_EMERG, "cdb_fetch(%d): %s\n", cdb,
+			db_strerror(ret));
+		abort();
 	}
-	if (ret != 0) return NULL;
-	tempcdb = (struct cdbdata *) mallok(sizeof(struct cdbdata));
+
+	if (ret != 0)
+		return NULL;
+	tempcdb = (struct cdbdata *) malloc(sizeof(struct cdbdata));
+
 	if (tempcdb == NULL) {
-		lprintf(2, "Cannot allocate memory!\n");
+		lprintf(CTDL_EMERG,
+			"cdb_fetch: Cannot allocate memory for tempcdb\n");
+		abort();
 	}
+
 	tempcdb->len = dret.size;
 	tempcdb->ptr = dret.data;
+#ifdef HAVE_ZLIB
+	cdb_decompress_if_necessary(tempcdb);
+#endif
 	return (tempcdb);
 }
 
 
 /*
- * Free a cdbdata item (ok, this is really no big deal, but we might need to do
- * more complex stuff with other database managers in the future).
+ * Free a cdbdata item.
+ *
+ * Note that we only free the 'ptr' portion if it is not NULL.  This allows
+ * other code to assume ownership of that memory simply by storing the
+ * pointer elsewhere and then setting 'ptr' to NULL.  cdb_free() will then
+ * avoid freeing it.
  */
 void cdb_free(struct cdbdata *cdb)
 {
-	phree(cdb->ptr);
-	phree(cdb);
+	if (cdb->ptr) {
+		free(cdb->ptr);
+	}
+	free(cdb);
 }
 
+void cdb_close_cursor(int cdb)
+{
+	if (MYCURSORS[cdb] != NULL)
+		cclose(MYCURSORS[cdb]);
+
+	MYCURSORS[cdb] = NULL;
+}
 
 /* 
- * Prepare for a sequential search of an entire database.  (In the DB model,
- * use per-session key. There is guaranteed to be no more than one traversal in
- * progress per session at any given time.)
+ * Prepare for a sequential search of an entire database.
+ * (There is guaranteed to be no more than one traversal in
+ * progress per thread at any given time.)
  */
 void cdb_rewind(int cdb)
 {
 	int ret = 0;
 
-	begin_critical_section(S_DATABASE);
-	ret = dbp[cdb]->cursor(dbp[cdb], NULL, &MYCURSOR, 0);
+	if (MYCURSORS[cdb] != NULL) {
+		lprintf(CTDL_EMERG,
+			"cdb_rewind: must close cursor on database %d before reopening.\n",
+			cdb);
+		abort();
+		/* cclose(MYCURSORS[cdb]); */
+	}
+
+	/*
+	 * Now initialize the cursor
+	 */
+	ret = dbp[cdb]->cursor(dbp[cdb], MYTID, &MYCURSORS[cdb], 0);
 	if (ret) {
-		lprintf(1, "db_cursor: %s\n", db_strerror(ret));
+		lprintf(CTDL_EMERG, "cdb_rewind: db_cursor: %s\n",
+			db_strerror(ret));
+		abort();
 	}
-	end_critical_section(S_DATABASE);
 }
 
 
@@ -300,23 +828,113 @@ struct cdbdata *cdb_next_item(int cdb)
 	struct cdbdata *cdbret;
 	int ret = 0;
 
-        /* Initialize the key/data pair so the flags aren't set. */
-        memset(&key, 0, sizeof(key));
-        memset(&data, 0, sizeof(data));
+	/* Initialize the key/data pair so the flags aren't set. */
+	memset(&key, 0, sizeof(key));
+	memset(&data, 0, sizeof(data));
 	data.flags = DB_DBT_MALLOC;
 
-	begin_critical_section(S_DATABASE);
-	lprintf(9, "cdb_next_item(%d)...\n", cdb);
-	ret = MYCURSOR->c_get(MYCURSOR,
-		&key, &data, DB_NEXT);
-	lprintf(9, "...returned %d\n", ret);
-	end_critical_section(S_DATABASE);
-	
-	if (ret) return NULL;		/* presumably, end of file */
+	ret = MYCURSORS[cdb]->c_get(MYCURSORS[cdb], &key, &data, DB_NEXT);
 
-	cdbret = (struct cdbdata *) mallok(sizeof(struct cdbdata));
+	if (ret) {
+		if (ret != DB_NOTFOUND) {
+			lprintf(CTDL_EMERG, "cdb_next_item(%d): %s\n",
+				cdb, db_strerror(ret));
+			abort();
+		}
+		cclose(MYCURSORS[cdb]);
+		MYCURSORS[cdb] = NULL;
+		return NULL;	/* presumably, end of file */
+	}
+
+	cdbret = (struct cdbdata *) malloc(sizeof(struct cdbdata));
 	cdbret->len = data.size;
 	cdbret->ptr = data.data;
+#ifdef HAVE_ZLIB
+	cdb_decompress_if_necessary(cdbret);
+#endif
 
 	return (cdbret);
 }
+
+
+
+/*
+ * Transaction-based stuff.  I'm writing this as I bake cookies...
+ */
+
+void cdb_begin_transaction(void)
+{
+
+	bailIfCursor(MYCURSORS,
+		     "can't begin transaction during r/o cursor");
+
+	if (MYTID != NULL) {
+		lprintf(CTDL_EMERG,
+			"cdb_begin_transaction: ERROR: nested transaction\n");
+		abort();
+	}
+
+	txbegin(&MYTID);
+}
+
+void cdb_end_transaction(void)
+{
+	int i;
+
+	for (i = 0; i < MAXCDB; i++)
+		if (MYCURSORS[i] != NULL) {
+			lprintf(CTDL_WARNING,
+				"cdb_end_transaction: WARNING: cursor %d still open at transaction end\n",
+				i);
+			cclose(MYCURSORS[i]);
+			MYCURSORS[i] = NULL;
+		}
+
+	if (MYTID == NULL) {
+		lprintf(CTDL_EMERG,
+			"cdb_end_transaction: ERROR: txcommit(NULL) !!\n");
+		abort();
+	} else
+		txcommit(MYTID);
+
+	MYTID = NULL;
+}
+
+/*
+ * Truncate (delete every record)
+ */
+void cdb_trunc(int cdb)
+{
+	/* DB_TXN *tid; */
+	int ret;
+	u_int32_t count;
+
+	if (MYTID != NULL) {
+		lprintf(CTDL_EMERG,
+			"cdb_trunc must not be called in a transaction.\n");
+		abort();
+	} else {
+		bailIfCursor(MYCURSORS,
+			     "attempt to write during r/o cursor");
+
+	      retry:
+		/* txbegin(&tid); */
+
+		if ((ret = dbp[cdb]->truncate(dbp[cdb],	/* db */
+					      NULL,	/* transaction ID */
+					      &count,	/* #rows deleted */
+					      0))) {	/* flags */
+			if (ret == DB_LOCK_DEADLOCK) {
+				/* txabort(tid); */
+				goto retry;
+			} else {
+				lprintf(CTDL_EMERG,
+					"cdb_truncate(%d): %s\n", cdb,
+					db_strerror(ret));
+				abort();
+			}
+		} else {
+			/* txcommit(tid); */
+		}
+	}
+}