WT-2962 Allow configuration of builtin extensions. (#3137)

While in the area, fix sending "config={values}" to extensions: just the values should be passed in.

14 files changed, 270 insertions, 222 deletions

diff --git a/dist/api_data.py b/dist/api_data.py
index 7016be374a8..5a81e8dd080 100644
--- a/dist/api_data.py
+++ b/dist/api_data.py
@@ -657,6 +657,11 @@ wiredtiger_open_common =\
         should be used (4KB on Linux systems when direct I/O is configured,
         zero elsewhere)''',
         min='-1', max='1MB'),
+    Config('builtin_extension_config', '', r'''
+        A structure where the keys are the names of builtin extensions and the
+        values are passed to WT_CONNECTION::load_extension as the \c config
+        parameter (for example,
+        <code>builtin_extension_config={zlib={compression_level=3}}</code>)'''),
     Config('checkpoint_sync', 'true', r'''
         flush files to stable storage when closing or writing
         checkpoints''',
diff --git a/examples/c/ex_file_system.c b/examples/c/ex_file_system.c
index 524a5d03f89..f51cad328c3 100644
--- a/examples/c/ex_file_system.c
+++ b/examples/c/ex_file_system.c
@@ -194,19 +194,9 @@ demo_file_system_create(WT_CONNECTION *conn, WT_CONFIG_ARG *config)
 	 * the underlying filesystem implementation. See the main function for
 	 * the setup of those configuration strings; here we parse configuration
 	 * information as passed in by main, through WiredTiger.
-	 *
-	 * Retrieve our configuration information, the "config" value.
 	 */
-	if ((ret = wtext->config_get(wtext, NULL, config, "config", &v)) != 0) {
-		(void)wtext->err_printf(wtext, NULL,
-		    "WT_EXTENSION_API.config_get: config: %s",
-		    wtext->strerror(wtext, NULL, ret));
-		goto err;
-	}
-
-	/* Open a WiredTiger parser on the "config" value. */
-	if ((ret = wtext->config_parser_open(
-	    wtext, NULL, v.str, v.len, &config_parser)) != 0) {
+	if ((ret = wtext->config_parser_open_arg(
+	    wtext, NULL, config, &config_parser)) != 0) {
 		(void)wtext->err_printf(wtext, NULL,
 		    "WT_EXTENSION_API.config_parser_open: config: %s",
 		    wtext->strerror(wtext, NULL, ret));
diff --git a/ext/compressors/zlib/zlib_compress.c b/ext/compressors/zlib/zlib_compress.c
index 3665ec48b9a..09a793646e7 100644
--- a/ext/compressors/zlib/zlib_compress.c
+++ b/ext/compressors/zlib/zlib_compress.c
@@ -483,8 +483,7 @@ static int
 zlib_init_config(
     WT_CONNECTION *connection, WT_CONFIG_ARG *config, int *zlib_levelp)
 {
-	WT_CONFIG_ITEM k, v;
-	WT_CONFIG_PARSER *config_parser;
+	WT_CONFIG_ITEM v;
 	WT_EXTENSION_API *wt_api;
 	int ret, zlib_level;
 
@@ -497,49 +496,27 @@ zlib_init_config(
 	 * level; review the configuration.
 	 */
 	wt_api = connection->get_extension_api(connection);
-	if ((ret =
-	    wt_api->config_get(wt_api, NULL, config, "config", &v)) != 0) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_EXTENSION_API.config_get: zlib configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	if ((ret = wt_api->config_parser_open(
-	    wt_api, NULL, v.str, v.len, &config_parser)) != 0) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_EXTENSION_API.config_parser_open: zlib configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	while ((ret = config_parser->next(config_parser, &k, &v)) == 0)
-		if (strlen("compression_level") == k.len &&
-		    strncmp("compression_level", k.str, k.len) == 0) {
-			/*
-			 * Between 0-9: level: see zlib manual.
-			 */
-			zlib_level = (int)v.val;
-			if (zlib_level < 0 || zlib_level > 9) {
-				(void)wt_api->err_printf(wt_api, NULL,
-				    "WT_CONFIG_PARSER.next: zlib configure: "
-				    "unsupported compression level %d",
-				    zlib_level);
-				return (EINVAL);
-			}
-			*zlib_levelp = zlib_level;
-			continue;
+	if ((ret = wt_api->config_get(
+	    wt_api, NULL, config, "compression_level", &v)) == 0) {
+		/*
+		 * Between 0-9: level: see zlib manual.
+		 */
+		zlib_level = (int)v.val;
+		if (zlib_level < 0 || zlib_level > 9) {
+			(void)wt_api->err_printf(wt_api, NULL,
+			    "zlib_init_config: "
+			    "unsupported compression level %d",
+			    zlib_level);
+			return (EINVAL);
 		}
-	if (ret != WT_NOTFOUND) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_CONFIG_PARSER.next: zlib configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	if ((ret = config_parser->close(config_parser)) != 0) {
+		*zlib_levelp = zlib_level;
+	} else if (ret != WT_NOTFOUND) {
 		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_CONFIG_PARSER.close: zlib configure: %s",
+		    "zlib_init_config: %s",
 		    wt_api->strerror(wt_api, NULL, ret));
 		return (ret);
 	}
+
 	return (0);
 }
 
diff --git a/ext/compressors/zstd/zstd_compress.c b/ext/compressors/zstd/zstd_compress.c
index a459b01d60a..ea8ec97602f 100644
--- a/ext/compressors/zstd/zstd_compress.c
+++ b/ext/compressors/zstd/zstd_compress.c
@@ -232,8 +232,7 @@ static int
 zstd_init_config(
     WT_CONNECTION *connection, WT_CONFIG_ARG *config, int *compression_levelp)
 {
-	WT_CONFIG_ITEM k, v;
-	WT_CONFIG_PARSER *config_parser;
+	WT_CONFIG_ITEM v;
 	WT_EXTENSION_API *wt_api;
 	int ret;
 
@@ -246,38 +245,16 @@ zstd_init_config(
 	 * level; review the configuration.
 	 */
 	wt_api = connection->get_extension_api(connection);
-	if ((ret =
-	    wt_api->config_get(wt_api, NULL, config, "config", &v)) != 0) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_EXTENSION_API.config_get: zstd configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	if ((ret = wt_api->config_parser_open(
-	    wt_api, NULL, v.str, v.len, &config_parser)) != 0) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_EXTENSION_API.config_parser_open: zstd configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	while ((ret = config_parser->next(config_parser, &k, &v)) == 0)
-		if (strlen("compression_level") == k.len &&
-		    strncmp("compression_level", k.str, k.len) == 0) {
-			*compression_levelp = (int)v.val;
-			continue;
-		}
-	if (ret != WT_NOTFOUND) {
+	if ((ret = wt_api->config_get(
+	    wt_api, NULL, config, "compression_level", &v)) == 0)
+		*compression_levelp = (int)v.val;
+	else if (ret != WT_NOTFOUND) {
 		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_CONFIG_PARSER.next: zstd configure: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-		return (ret);
-	}
-	if ((ret = config_parser->close(config_parser)) != 0) {
-		(void)wt_api->err_printf(wt_api, NULL,
-		    "WT_CONFIG_PARSER.close: zstd configure: %s",
+		    "zstd_init_config: %s",
 		    wt_api->strerror(wt_api, NULL, ret));
 		return (ret);
 	}
+
 	return (0);
 }
 
diff --git a/ext/datasources/helium/helium.c b/ext/datasources/helium/helium.c
index 473c569f0cc..dff86bd73ac 100644
--- a/ext/datasources/helium/helium.c
+++ b/ext/datasources/helium/helium.c
@@ -3380,15 +3380,9 @@ wiredtiger_extension_init(WT_CONNECTION *connection, WT_CONFIG_ARG *config)
 		goto err;
 	ds->lockinit = 1;
 
-	/* Get the configuration string. */
-	if ((ret = wt_api->config_get(wt_api, NULL, config, "config", &v)) != 0)
-		EMSG_ERR(wt_api, NULL, ret,
-		    "WT_EXTENSION_API.config_get: config: %s",
-		    wt_api->strerror(wt_api, NULL, ret));
-
 	/* Step through the list of Helium sources, opening each one. */
-	if ((ret = wt_api->config_parser_open(
-	    wt_api, NULL, v.str, v.len, &config_parser)) != 0)
+	if ((ret = wt_api->config_parser_open_arg(
+	    wt_api, NULL, config, &config_parser)) != 0)
 		EMSG_ERR(wt_api, NULL, ret,
 		    "WT_EXTENSION_API.config_parser_open: config: %s",
 		    wt_api->strerror(wt_api, NULL, ret));
diff --git a/ext/encryptors/rotn/rotn_encrypt.c b/ext/encryptors/rotn/rotn_encrypt.c
index 559c8e6e33a..0b905a0540d 100644
--- a/ext/encryptors/rotn/rotn_encrypt.c
+++ b/ext/encryptors/rotn/rotn_encrypt.c
@@ -76,7 +76,7 @@ typedef struct {
 	u_char *shift_forw;		/* Encrypt shift data from secretkey */
 	u_char *shift_back;		/* Decrypt shift data from secretkey */
 	size_t shift_len;		/* Length of shift* byte arrays */
-	int force_error;		/* Force a decrypt error for testing */
+	bool force_error;		/* Force a decrypt error for testing */
 
 } ROTN_ENCRYPTOR;
 /*! [WT_ENCRYPTOR initialization structure] */
@@ -429,43 +429,19 @@ rotn_terminate(WT_ENCRYPTOR *encryptor, WT_SESSION *session)
 static int
 rotn_configure(ROTN_ENCRYPTOR *rotn_encryptor, WT_CONFIG_ARG *config)
 {
-	WT_CONFIG_ITEM k, v;
-	WT_CONFIG_PARSER *config_parser;
+	WT_CONFIG_ITEM v;
 	WT_EXTENSION_API *wt_api;	/* Extension API */
-	int ret, t_ret;
+	int ret;
 
 	wt_api = rotn_encryptor->wt_api;
 
 	/* Get the configuration string. */
-	if ((ret = wt_api->config_get(wt_api, NULL, config, "config", &v)) != 0)
-		return (rotn_error(rotn_encryptor, NULL, ret,
-		    "WT_EXTENSION_API.config_get"));
-
-	/* Step through the list of configuration options. */
-	if ((ret = wt_api->config_parser_open(
-	    wt_api, NULL, v.str, v.len, &config_parser)) != 0)
-		return (rotn_error(rotn_encryptor, NULL, ret,
-		    "WT_EXTENSION_API.config_parser_open"));
-
-	while ((ret = config_parser->next(config_parser, &k, &v)) == 0) {
-		if (strncmp("rotn_force_error", k.str, k.len) == 0 &&
-		    strlen("rotn_force_error") == k.len) {
-			rotn_encryptor->force_error = v.val == 0 ? 0 : 1;
-			continue;
-		} else {
-			if ((ret = config_parser->close(config_parser)) != 0)
-				return (rotn_error(rotn_encryptor,
-				    NULL, ret, "WT_CONFIG_PARSER.close"));
-			return (rotn_error(rotn_encryptor, NULL, EINVAL,
-			    "unknown config key"));
-		}
-	}
-	if ((t_ret = config_parser->close(config_parser)) != 0)
-		return (rotn_error(rotn_encryptor, NULL, t_ret,
-		    "WT_CONFIG_PARSER.close"));
-	if (ret != WT_NOTFOUND)
-		return (rotn_error(rotn_encryptor, NULL, ret,
-		    "WT_CONFIG_PARSER.next"));
+	if ((ret = wt_api->config_get(
+	    wt_api, NULL, config, "rotn_force_error", &v)) == 0)
+		rotn_encryptor->force_error = v.val != 0;
+	else if (ret != WT_NOTFOUND)
+		return (rotn_error(rotn_encryptor, NULL, EINVAL,
+		    "error parsing config"));
 
 	return (0);
 }
diff --git a/src/config/config.c b/src/config/config.c
index 3416153d160..a47dfe76aec 100644
--- a/src/config/config.c
+++ b/src/config/config.c
@@ -711,7 +711,7 @@ __wt_config_getones(WT_SESSION_IMPL *session,
 /*
  * __wt_config_getones_none --
  *	Get the value for a given string key from a single config string.
- * Treat "none" as empty.
+ *	Treat "none" as empty.
  */
 int
 __wt_config_getones_none(WT_SESSION_IMPL *session,
diff --git a/src/config/config_def.c b/src/config/config_def.c
index 540cf846e90..35fea16b1a5 100644
--- a/src/config/config_def.c
+++ b/src/config/config_def.c
@@ -659,6 +659,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open[] = {
 	    NULL, NULL,
 	    confchk_wiredtiger_open_async_subconfigs, 3 },
 	{ "buffer_alignment", "int", NULL, "min=-1,max=1MB", NULL, 0 },
+	{ "builtin_extension_config", "string", NULL, NULL, NULL, 0 },
 	{ "cache_overhead", "int", NULL, "min=0,max=30", NULL, 0 },
 	{ "cache_size", "int", NULL, "min=1MB,max=10TB", NULL, 0 },
 	{ "checkpoint", "category",
@@ -744,6 +745,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open_all[] = {
 	    NULL, NULL,
 	    confchk_wiredtiger_open_async_subconfigs, 3 },
 	{ "buffer_alignment", "int", NULL, "min=-1,max=1MB", NULL, 0 },
+	{ "builtin_extension_config", "string", NULL, NULL, NULL, 0 },
 	{ "cache_overhead", "int", NULL, "min=0,max=30", NULL, 0 },
 	{ "cache_size", "int", NULL, "min=1MB,max=10TB", NULL, 0 },
 	{ "checkpoint", "category",
@@ -830,6 +832,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open_basecfg[] = {
 	    NULL, NULL,
 	    confchk_wiredtiger_open_async_subconfigs, 3 },
 	{ "buffer_alignment", "int", NULL, "min=-1,max=1MB", NULL, 0 },
+	{ "builtin_extension_config", "string", NULL, NULL, NULL, 0 },
 	{ "cache_overhead", "int", NULL, "min=0,max=30", NULL, 0 },
 	{ "cache_size", "int", NULL, "min=1MB,max=10TB", NULL, 0 },
 	{ "checkpoint", "category",
@@ -910,6 +913,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open_usercfg[] = {
 	    NULL, NULL,
 	    confchk_wiredtiger_open_async_subconfigs, 3 },
 	{ "buffer_alignment", "int", NULL, "min=-1,max=1MB", NULL, 0 },
+	{ "builtin_extension_config", "string", NULL, NULL, NULL, 0 },
 	{ "cache_overhead", "int", NULL, "min=0,max=30", NULL, 0 },
 	{ "cache_size", "int", NULL, "min=1MB,max=10TB", NULL, 0 },
 	{ "checkpoint", "category",
@@ -1228,62 +1232,64 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	},
 	{ "wiredtiger_open",
 	  "async=(enabled=false,ops_max=1024,threads=2),buffer_alignment=-1"
-	  ",cache_overhead=8,cache_size=100MB,checkpoint=(log_size=0,"
-	  "wait=0),checkpoint_sync=true,config_base=true,create=false,"
-	  "direct_io=,encryption=(keyid=,name=,secretkey=),error_prefix=,"
-	  "eviction=(threads_max=1,threads_min=1),"
-	  "eviction_checkpoint_target=5,eviction_dirty_target=5,"
-	  "eviction_dirty_trigger=20,eviction_target=80,eviction_trigger=95"
-	  ",exclusive=false,extensions=,file_extend=,"
-	  "file_manager=(close_handle_minimum=250,close_idle_time=30,"
-	  "close_scan_interval=10),hazard_max=1000,in_memory=false,"
-	  "log=(archive=true,compressor=,enabled=false,file_max=100MB,"
-	  "path=\".\",prealloc=true,recover=on,zero_fill=false),"
-	  "lsm_manager=(merge=true,worker_thread_max=4),lsm_merge=true,"
-	  "mmap=true,multiprocess=false,readonly=false,session_max=100,"
-	  "session_scratch_max=2MB,shared_cache=(chunk=10MB,name=,quota=0,"
-	  "reserve=0,size=500MB),statistics=none,statistics_log=(json=false"
-	  ",on_close=false,path=\".\",sources=,timestamp=\"%b %d %H:%M:%S\""
-	  ",wait=0),transaction_sync=(enabled=false,method=fsync),"
+	  ",builtin_extension_config=,cache_overhead=8,cache_size=100MB,"
+	  "checkpoint=(log_size=0,wait=0),checkpoint_sync=true,"
+	  "config_base=true,create=false,direct_io=,encryption=(keyid=,"
+	  "name=,secretkey=),error_prefix=,eviction=(threads_max=1,"
+	  "threads_min=1),eviction_checkpoint_target=5,"
+	  "eviction_dirty_target=5,eviction_dirty_trigger=20,"
+	  "eviction_target=80,eviction_trigger=95,exclusive=false,"
+	  "extensions=,file_extend=,file_manager=(close_handle_minimum=250,"
+	  "close_idle_time=30,close_scan_interval=10),hazard_max=1000,"
+	  "in_memory=false,log=(archive=true,compressor=,enabled=false,"
+	  "file_max=100MB,path=\".\",prealloc=true,recover=on,"
+	  "zero_fill=false),lsm_manager=(merge=true,worker_thread_max=4),"
+	  "lsm_merge=true,mmap=true,multiprocess=false,readonly=false,"
+	  "session_max=100,session_scratch_max=2MB,shared_cache=(chunk=10MB"
+	  ",name=,quota=0,reserve=0,size=500MB),statistics=none,"
+	  "statistics_log=(json=false,on_close=false,path=\".\",sources=,"
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),"
+	  "transaction_sync=(enabled=false,method=fsync),"
 	  "use_environment=true,use_environment_priv=false,verbose=,"
 	  "write_through=",
-	  confchk_wiredtiger_open, 39
+	  confchk_wiredtiger_open, 40
 	},
 	{ "wiredtiger_open_all",
 	  "async=(enabled=false,ops_max=1024,threads=2),buffer_alignment=-1"
-	  ",cache_overhead=8,cache_size=100MB,checkpoint=(log_size=0,"
-	  "wait=0),checkpoint_sync=true,config_base=true,create=false,"
-	  "direct_io=,encryption=(keyid=,name=,secretkey=),error_prefix=,"
-	  "eviction=(threads_max=1,threads_min=1),"
-	  "eviction_checkpoint_target=5,eviction_dirty_target=5,"
-	  "eviction_dirty_trigger=20,eviction_target=80,eviction_trigger=95"
-	  ",exclusive=false,extensions=,file_extend=,"
-	  "file_manager=(close_handle_minimum=250,close_idle_time=30,"
-	  "close_scan_interval=10),hazard_max=1000,in_memory=false,"
-	  "log=(archive=true,compressor=,enabled=false,file_max=100MB,"
-	  "path=\".\",prealloc=true,recover=on,zero_fill=false),"
-	  "lsm_manager=(merge=true,worker_thread_max=4),lsm_merge=true,"
-	  "mmap=true,multiprocess=false,readonly=false,session_max=100,"
-	  "session_scratch_max=2MB,shared_cache=(chunk=10MB,name=,quota=0,"
-	  "reserve=0,size=500MB),statistics=none,statistics_log=(json=false"
-	  ",on_close=false,path=\".\",sources=,timestamp=\"%b %d %H:%M:%S\""
-	  ",wait=0),transaction_sync=(enabled=false,method=fsync),"
+	  ",builtin_extension_config=,cache_overhead=8,cache_size=100MB,"
+	  "checkpoint=(log_size=0,wait=0),checkpoint_sync=true,"
+	  "config_base=true,create=false,direct_io=,encryption=(keyid=,"
+	  "name=,secretkey=),error_prefix=,eviction=(threads_max=1,"
+	  "threads_min=1),eviction_checkpoint_target=5,"
+	  "eviction_dirty_target=5,eviction_dirty_trigger=20,"
+	  "eviction_target=80,eviction_trigger=95,exclusive=false,"
+	  "extensions=,file_extend=,file_manager=(close_handle_minimum=250,"
+	  "close_idle_time=30,close_scan_interval=10),hazard_max=1000,"
+	  "in_memory=false,log=(archive=true,compressor=,enabled=false,"
+	  "file_max=100MB,path=\".\",prealloc=true,recover=on,"
+	  "zero_fill=false),lsm_manager=(merge=true,worker_thread_max=4),"
+	  "lsm_merge=true,mmap=true,multiprocess=false,readonly=false,"
+	  "session_max=100,session_scratch_max=2MB,shared_cache=(chunk=10MB"
+	  ",name=,quota=0,reserve=0,size=500MB),statistics=none,"
+	  "statistics_log=(json=false,on_close=false,path=\".\",sources=,"
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),"
+	  "transaction_sync=(enabled=false,method=fsync),"
 	  "use_environment=true,use_environment_priv=false,verbose=,"
 	  "version=(major=0,minor=0),write_through=",
-	  confchk_wiredtiger_open_all, 40
+	  confchk_wiredtiger_open_all, 41
 	},
 	{ "wiredtiger_open_basecfg",
 	  "async=(enabled=false,ops_max=1024,threads=2),buffer_alignment=-1"
-	  ",cache_overhead=8,cache_size=100MB,checkpoint=(log_size=0,"
-	  "wait=0),checkpoint_sync=true,direct_io=,encryption=(keyid=,name="
-	  ",secretkey=),error_prefix=,eviction=(threads_max=1,"
-	  "threads_min=1),eviction_checkpoint_target=5,"
-	  "eviction_dirty_target=5,eviction_dirty_trigger=20,"
-	  "eviction_target=80,eviction_trigger=95,extensions=,file_extend=,"
-	  "file_manager=(close_handle_minimum=250,close_idle_time=30,"
-	  "close_scan_interval=10),hazard_max=1000,log=(archive=true,"
-	  "compressor=,enabled=false,file_max=100MB,path=\".\","
-	  "prealloc=true,recover=on,zero_fill=false),"
+	  ",builtin_extension_config=,cache_overhead=8,cache_size=100MB,"
+	  "checkpoint=(log_size=0,wait=0),checkpoint_sync=true,direct_io=,"
+	  "encryption=(keyid=,name=,secretkey=),error_prefix=,"
+	  "eviction=(threads_max=1,threads_min=1),"
+	  "eviction_checkpoint_target=5,eviction_dirty_target=5,"
+	  "eviction_dirty_trigger=20,eviction_target=80,eviction_trigger=95"
+	  ",extensions=,file_extend=,file_manager=(close_handle_minimum=250"
+	  ",close_idle_time=30,close_scan_interval=10),hazard_max=1000,"
+	  "log=(archive=true,compressor=,enabled=false,file_max=100MB,"
+	  "path=\".\",prealloc=true,recover=on,zero_fill=false),"
 	  "lsm_manager=(merge=true,worker_thread_max=4),lsm_merge=true,"
 	  "mmap=true,multiprocess=false,readonly=false,session_max=100,"
 	  "session_scratch_max=2MB,shared_cache=(chunk=10MB,name=,quota=0,"
@@ -1291,20 +1297,20 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  ",on_close=false,path=\".\",sources=,timestamp=\"%b %d %H:%M:%S\""
 	  ",wait=0),transaction_sync=(enabled=false,method=fsync),verbose=,"
 	  "version=(major=0,minor=0),write_through=",
-	  confchk_wiredtiger_open_basecfg, 34
+	  confchk_wiredtiger_open_basecfg, 35
 	},
 	{ "wiredtiger_open_usercfg",
 	  "async=(enabled=false,ops_max=1024,threads=2),buffer_alignment=-1"
-	  ",cache_overhead=8,cache_size=100MB,checkpoint=(log_size=0,"
-	  "wait=0),checkpoint_sync=true,direct_io=,encryption=(keyid=,name="
-	  ",secretkey=),error_prefix=,eviction=(threads_max=1,"
-	  "threads_min=1),eviction_checkpoint_target=5,"
-	  "eviction_dirty_target=5,eviction_dirty_trigger=20,"
-	  "eviction_target=80,eviction_trigger=95,extensions=,file_extend=,"
-	  "file_manager=(close_handle_minimum=250,close_idle_time=30,"
-	  "close_scan_interval=10),hazard_max=1000,log=(archive=true,"
-	  "compressor=,enabled=false,file_max=100MB,path=\".\","
-	  "prealloc=true,recover=on,zero_fill=false),"
+	  ",builtin_extension_config=,cache_overhead=8,cache_size=100MB,"
+	  "checkpoint=(log_size=0,wait=0),checkpoint_sync=true,direct_io=,"
+	  "encryption=(keyid=,name=,secretkey=),error_prefix=,"
+	  "eviction=(threads_max=1,threads_min=1),"
+	  "eviction_checkpoint_target=5,eviction_dirty_target=5,"
+	  "eviction_dirty_trigger=20,eviction_target=80,eviction_trigger=95"
+	  ",extensions=,file_extend=,file_manager=(close_handle_minimum=250"
+	  ",close_idle_time=30,close_scan_interval=10),hazard_max=1000,"
+	  "log=(archive=true,compressor=,enabled=false,file_max=100MB,"
+	  "path=\".\",prealloc=true,recover=on,zero_fill=false),"
 	  "lsm_manager=(merge=true,worker_thread_max=4),lsm_merge=true,"
 	  "mmap=true,multiprocess=false,readonly=false,session_max=100,"
 	  "session_scratch_max=2MB,shared_cache=(chunk=10MB,name=,quota=0,"
@@ -1312,7 +1318,7 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  ",on_close=false,path=\".\",sources=,timestamp=\"%b %d %H:%M:%S\""
 	  ",wait=0),transaction_sync=(enabled=false,method=fsync),verbose=,"
 	  "write_through=",
-	  confchk_wiredtiger_open_usercfg, 33
+	  confchk_wiredtiger_open_usercfg, 34
 	},
 	{ NULL, NULL, NULL, 0 }
 };
diff --git a/src/config/config_ext.c b/src/config/config_ext.c
index 56c0018f8c3..88f1390843a 100644
--- a/src/config/config_ext.c
+++ b/src/config/config_ext.c
@@ -9,22 +9,9 @@
 #include "wt_internal.h"
 
 /*
- * __wt_ext_config_parser_open --
- *	WT_EXTENSION_API->config_parser_open implementation
- */
-int
-__wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session,
-    const char *config, size_t len, WT_CONFIG_PARSER **config_parserp)
-{
-	WT_UNUSED(wt_ext);
-	return (wiredtiger_config_parser_open(
-	    wt_session, config, len, config_parserp));
-}
-
-/*
  * __wt_ext_config_get --
  *	Given a NULL-terminated list of configuration strings, find the final
- * value for a given string key (external API version).
+ *	value for a given string key (external API version).
  */
 int
 __wt_ext_config_get(WT_EXTENSION_API *wt_api,
@@ -43,3 +30,65 @@ __wt_ext_config_get(WT_EXTENSION_API *wt_api,
 		return (WT_NOTFOUND);
 	return (__wt_config_gets(session, cfg, key, cval));
 }
+
+/*
+ * __wt_ext_config_get_string --
+ *	Given a configuration string, find the value for a given string key
+ *	(external API version).
+ */
+int
+__wt_ext_config_get_string(WT_EXTENSION_API *wt_api,
+    WT_SESSION *wt_session, const char *config, const char *key,
+    WT_CONFIG_ITEM *cval)
+{
+	WT_CONNECTION_IMPL *conn;
+	WT_SESSION_IMPL *session;
+
+	conn = (WT_CONNECTION_IMPL *)wt_api->conn;
+	if ((session = (WT_SESSION_IMPL *)wt_session) == NULL)
+		session = conn->default_session;
+
+	return (__wt_config_getones(session, config, key, cval));
+}
+
+/*
+ * __wt_ext_config_parser_open --
+ *	WT_EXTENSION_API->config_parser_open implementation
+ */
+int
+__wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session,
+    const char *config, size_t len, WT_CONFIG_PARSER **config_parserp)
+{
+	WT_UNUSED(wt_ext);
+	return (wiredtiger_config_parser_open(
+	    wt_session, config, len, config_parserp));
+}
+
+/*
+ * __wt_ext_config_parser_open_arg --
+ *	WT_EXTENSION_API->config_parser_open_arg implementation
+ */
+int
+__wt_ext_config_parser_open_arg(WT_EXTENSION_API *wt_ext,
+    WT_SESSION *wt_session, WT_CONFIG_ARG *cfg_arg,
+    WT_CONFIG_PARSER **config_parserp)
+{
+	const char **cfg, *p;
+	size_t len;
+
+	WT_UNUSED(wt_ext);
+
+	/* Find the last non-NULL entry in the configuration stack. */
+	if ((cfg = (const char **)cfg_arg) == NULL || *cfg == NULL) {
+		p = NULL;
+		len = 0;
+	} else {
+		while (cfg[1] != NULL)
+			++cfg;
+		p = *cfg;
+		len = strlen(p);
+	}
+
+	return (wiredtiger_config_parser_open(
+	    wt_session, p, len, config_parserp));
+}
diff --git a/src/conn/conn_api.c b/src/conn/conn_api.c
index 494735faaf0..dcb5fc74921 100644
--- a/src/conn/conn_api.c
+++ b/src/conn/conn_api.c
@@ -754,8 +754,11 @@ __conn_get_extension_api(WT_CONNECTION *wt_conn)
 	conn->extension_api.scr_free = __wt_ext_scr_free;
 	conn->extension_api.collator_config = ext_collator_config;
 	conn->extension_api.collate = ext_collate;
-	conn->extension_api.config_parser_open = __wt_ext_config_parser_open;
 	conn->extension_api.config_get = __wt_ext_config_get;
+	conn->extension_api.config_get_string = __wt_ext_config_get_string;
+	conn->extension_api.config_parser_open = __wt_ext_config_parser_open;
+	conn->extension_api.config_parser_open_arg =
+	    __wt_ext_config_parser_open_arg;
 	conn->extension_api.metadata_insert = __wt_ext_metadata_insert;
 	conn->extension_api.metadata_remove = __wt_ext_metadata_remove;
 	conn->extension_api.metadata_search = __wt_ext_metadata_search;
@@ -787,40 +790,75 @@ __conn_get_extension_api(WT_CONNECTION *wt_conn)
 	return (&conn->extension_api);
 }
 
+/*
+ * __conn_builtin_init --
+ *	Initialize and configure a builtin extension.
+ */
+static int
+__conn_builtin_init(WT_CONNECTION_IMPL *conn, const char *name,
+    int (*extension_init)(WT_CONNECTION *, WT_CONFIG_ARG *),
+    const char *cfg[])
+{
+	WT_CONFIG_ITEM all_configs, cval;
+	WT_DECL_RET;
+	WT_SESSION_IMPL *session;
+	char *config;
+	const char *ext_cfg[] = { NULL, NULL };
+
+	session = conn->default_session;
+
+	WT_RET(__wt_config_gets(
+	    session, cfg, "builtin_extension_config", &all_configs));
+	WT_CLEAR(cval);
+	WT_RET_NOTFOUND_OK(__wt_config_subgets(
+	    session, &all_configs, name, &cval));
+	WT_RET(__wt_strndup(session, cval.str, cval.len, &config));
+	ext_cfg[0] = config;
+
+	ret = extension_init(&conn->iface, (WT_CONFIG_ARG *)ext_cfg);
+	__wt_free(session, config);
+
+	return (ret);
+}
+
 #ifdef HAVE_BUILTIN_EXTENSION_LZ4
-	extern int lz4_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
+extern int lz4_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_SNAPPY
-	extern int snappy_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
+extern int snappy_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_ZLIB
-	extern int zlib_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
+extern int zlib_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_ZSTD
-	extern int zstd_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
+extern int zstd_extension_init(WT_CONNECTION *, WT_CONFIG_ARG *);
 #endif
 
 /*
- * __conn_load_default_extensions --
+ * __conn_builtin_extensions --
  *	Load extensions that are enabled via --with-builtins
  */
 static int
-__conn_load_default_extensions(WT_CONNECTION_IMPL *conn)
+__conn_builtin_extensions(WT_CONNECTION_IMPL *conn, const char *cfg[])
 {
-	WT_UNUSED(conn);
-
 #ifdef HAVE_BUILTIN_EXTENSION_LZ4
-	WT_RET(lz4_extension_init(&conn->iface, NULL));
+	WT_RET(__conn_builtin_init(conn, "lz4", lz4_extension_init, cfg));
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_SNAPPY
-	WT_RET(snappy_extension_init(&conn->iface, NULL));
+	WT_RET(__conn_builtin_init(conn, "snappy", snappy_extension_init, cfg));
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_ZLIB
-	WT_RET(zlib_extension_init(&conn->iface, NULL));
+	WT_RET(__conn_builtin_init(conn, "zlib", zlib_extension_init, cfg));
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_ZSTD
-	WT_RET(zstd_extension_init(&conn->iface, NULL));
+	WT_RET(__conn_builtin_init(conn, "zstd", zstd_extension_init, cfg));
 #endif
+
+	/* Avoid warnings if no builtin extensions are configured. */
+	WT_UNUSED(conn);
+	WT_UNUSED(cfg);
+	WT_UNUSED(__conn_builtin_init);
+
 	return (0);
 }
 
@@ -837,10 +875,11 @@ __conn_load_extension_int(WT_SESSION_IMPL *session,
 	WT_DLH *dlh;
 	int (*load)(WT_CONNECTION *, WT_CONFIG_ARG *);
 	bool is_local;
-	const char *init_name, *terminate_name;
+	const char *ext_config, *init_name, *terminate_name;
+	const char *ext_cfg[2];
 
 	dlh = NULL;
-	init_name = terminate_name = NULL;
+	ext_config = init_name = terminate_name = NULL;
 	is_local = strcmp(path, "local") == 0;
 
 	/* Ensure that the load matches the phase of startup we are in. */
@@ -870,8 +909,14 @@ __conn_load_extension_int(WT_SESSION_IMPL *session,
 	WT_ERR(
 	    __wt_dlsym(session, dlh, terminate_name, false, &dlh->terminate));
 
+	WT_CLEAR(cval);
+	WT_ERR_NOTFOUND_OK(__wt_config_gets(session, cfg, "config", &cval));
+	WT_ERR(__wt_strndup(session, cval.str, cval.len, &ext_config));
+	ext_cfg[0] = ext_config;
+	ext_cfg[1] = NULL;
+
 	/* Call the load function last, it simplifies error handling. */
-	WT_ERR(load(&S2C(session)->iface, (WT_CONFIG_ARG *)cfg));
+	WT_ERR(load(&S2C(session)->iface, (WT_CONFIG_ARG *)ext_cfg));
 
 	/* Link onto the environment's list of open libraries. */
 	__wt_spin_lock(session, &S2C(session)->api_lock);
@@ -2353,7 +2398,7 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	 * everything else to be in place, and the extensions call back into the
 	 * library.
 	 */
-	WT_ERR(__conn_load_default_extensions(conn));
+	WT_ERR(__conn_builtin_extensions(conn, cfg));
 	WT_ERR(__conn_load_extensions(session, cfg, false));
 
 	/*
diff --git a/src/include/extern.h b/src/include/extern.h
index 63eaa5e39a4..ef2e9efa9fd 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -226,8 +226,10 @@ extern int __wt_config_merge(WT_SESSION_IMPL *session, const char **cfg, const c
 extern int __wt_conn_config_init(WT_SESSION_IMPL *session) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern void __wt_conn_config_discard(WT_SESSION_IMPL *session);
 extern const WT_CONFIG_ENTRY *__wt_conn_config_match(const char *method);
-extern int __wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session, const char *config, size_t len, WT_CONFIG_PARSER **config_parserp) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern int __wt_ext_config_get(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, WT_CONFIG_ARG *cfg_arg, const char *key, WT_CONFIG_ITEM *cval) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
+extern int __wt_ext_config_get_string(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, const char *config, const char *key, WT_CONFIG_ITEM *cval) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
+extern int __wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session, const char *config, size_t len, WT_CONFIG_PARSER **config_parserp) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
+extern int __wt_ext_config_parser_open_arg(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session, WT_CONFIG_ARG *cfg_arg, WT_CONFIG_PARSER **config_parserp) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern int __wt_config_upgrade(WT_SESSION_IMPL *session, WT_ITEM *buf) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern const char *__wt_wiredtiger_error(int error);
 extern int __wt_collator_config(WT_SESSION_IMPL *session, const char *uri, WT_CONFIG_ITEM *cname, WT_CONFIG_ITEM *metadata, WT_COLLATOR **collatorp, int *ownp) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in
index 296e510d8d4..8da46582924 100644
--- a/src/include/wiredtiger.in
+++ b/src/include/wiredtiger.in
@@ -2214,6 +2214,11 @@ struct __wt_connection {
  * I/O. The default value of -1 indicates a platform-specific alignment value
  * should be used (4KB on Linux systems when direct I/O is configured\, zero
  * elsewhere)., an integer between -1 and 1MB; default \c -1.}
+ * @config{builtin_extension_config, A structure where the keys are the names of
+ * builtin extensions and the values are passed to WT_CONNECTION::load_extension
+ * as the \c config parameter (for example\,
+ * <code>builtin_extension_config={zlib={compression_level=3}}</code>)., a
+ * string; default empty.}
  * @config{cache_overhead, assume the heap allocator overhead is the specified
  * percentage\, and adjust the cache usage by that amount (for example\, if
  * there is 10GB of data in cache\, a percentage of 10 means WiredTiger treats
diff --git a/src/include/wiredtiger_ext.h b/src/include/wiredtiger_ext.h
index 3d65cd1fc24..236d4e07e67 100644
--- a/src/include/wiredtiger_ext.h
+++ b/src/include/wiredtiger_ext.h
@@ -204,25 +204,47 @@ struct __wt_extension_api {
 	    WT_COLLATOR *collator, WT_ITEM *first, WT_ITEM *second, int *cmp);
 
 	/*!
-	 * @copydoc wiredtiger_config_parser_open
+	 * Return the value of a configuration key.
+	 *
+	 * @param wt_api the extension handle
+	 * @param session the session handle (or NULL if none available)
+	 * @param config the configuration information passed to an application
+	 * @param key configuration key string
+	 * @param value the returned value
+	 * @errors
+	 *
+	 * @snippet ex_data_source.c WT_EXTENSION config_get
 	 */
-	int (*config_parser_open)(WT_EXTENSION_API *wt_api, WT_SESSION *session,
-	    const char *config, size_t len, WT_CONFIG_PARSER **config_parserp);
+	int (*config_get)(WT_EXTENSION_API *wt_api, WT_SESSION *session,
+	    WT_CONFIG_ARG *config, const char *key, WT_CONFIG_ITEM *value);
 
 	/*!
-	 * Return the value of a configuration string.
+	 * Return the value of a configuration key from a string.
 	 *
 	 * @param wt_api the extension handle
 	 * @param session the session handle (or NULL if none available)
+	 * @param config the configuration string
 	 * @param key configuration key string
-	 * @param config the configuration information passed to an application
 	 * @param value the returned value
 	 * @errors
 	 *
 	 * @snippet ex_data_source.c WT_EXTENSION config_get
 	 */
-	int (*config_get)(WT_EXTENSION_API *wt_api, WT_SESSION *session,
-	    WT_CONFIG_ARG *config, const char *key, WT_CONFIG_ITEM *value);
+	int (*config_get_string)(WT_EXTENSION_API *wt_api, WT_SESSION *session,
+	    const char *config, const char *key, WT_CONFIG_ITEM *value);
+
+	/*!
+	 * @copydoc wiredtiger_config_parser_open
+	 */
+	int (*config_parser_open)(WT_EXTENSION_API *wt_api, WT_SESSION *session,
+	    const char *config, size_t len, WT_CONFIG_PARSER **config_parserp);
+
+	/*!
+	 * @copydoc wiredtiger_config_parser_open
+	 */
+	int (*config_parser_open_arg)(WT_EXTENSION_API *wt_api,
+	    WT_SESSION *session, WT_CONFIG_ARG *config,
+	    WT_CONFIG_PARSER **config_parserp);
 
 	/*!
 	 * Insert a row into the metadata if it does not already exist.
diff --git a/test/format/config.c b/test/format/config.c
index 839ff5058de..cf922b5db04 100644
--- a/test/format/config.c
+++ b/test/format/config.c
@@ -301,7 +301,7 @@ config_compression(const char *conf_name)
 		break;
 #endif
 #ifdef HAVE_BUILTIN_EXTENSION_ZSTD
-	case 15: case 16 case 17:		/* 15% zstd */
+	case 15: case 16: case 17:		/* 15% zstd */
 		cstr = "zstd";
 		break;
 #endif