Add new BiF for low-level Bloom filter initialization.

For symmetry reasons, the new Bif bloomfilter_basic_init2 also allows users to
manually specify the memory bounds and number of hash functions to use.

NEWS

@@ -113,6 +113,7 @@ New Functionality
   the frequency of elements. The corresponding functions are:
 
     bloomfilter_basic_init(fp: double, capacity: count, name: string &default=""): opaque of bloomfilter
+    bloomfilter_basic_init2(k: count, cells: count, name: string &default=""): opaque of bloomfilter
     bloomfilter_counting_init(k: count, cells: count, max: count, name: string &default=""): opaque of bloomfilter
     bloomfilter_add(bf: opaque of bloomfilter, x: any)
     bloomfilter_lookup(bf: opaque of bloomfilter, x: any): count

src/probabilistic/bloom-filter.bif

@@ -35,8 +35,8 @@ module GLOBAL;
 ##
 ## Returns: A Bloom filter handle.
 ##
-## .. bro:see:: bloomfilter_counting_init  bloomfilter_add bloomfilter_lookup
+## .. bro:see:: bloomfilter_basic_init2 bloomfilter_counting_init bloomfilter_add
-##    bloomfilter_clear bloomfilter_merge
+##    bloomfilter_lookup bloomfilter_clear bloomfilter_merge
 function bloomfilter_basic_init%(fp: double, capacity: count,
                                  name: string &default=""%): opaque of bloomfilter
 	%{
@@ -55,6 +55,47 @@ function bloomfilter_basic_init%(fp: double, capacity: count,
 	return new BloomFilterVal(new BasicBloomFilter(h, cells));
 	%}
 
+## Creates a basic Bloom filter. This function serves as a low-level
+## alternative to bloomfilter_basic_init where the user has full control over
+## the number of hash functions and cells in the underlying bit vector.
+##
+## .. note:: A Bloom filter can have a name associated with it. In the future,
+##    Bloom filters with the same name will be compatible across indepedent Bro
+##    instances, i.e., it will be possible to merge them. Currently, however, that is
+##    not yet supported.
+##
+## k: The number of hash functions to use.
+##
+## cells: The number of cells of the underlying bit vector.
+##
+## name: A name that uniquely identifies and seeds the Bloom filter. If empty,
+## the filter will remain tied to the current Bro process.
+##
+## Returns: A Bloom filter handle.
+##
+## .. bro:see:: bloom_filter_basic_init bloomfilter_counting_init  bloomfilter_add 
+##    bloomfilter_lookup bloomfilter_clear bloomfilter_merge
+function bloomfilter_basic_init2%(k: count, cells: count,
+                                  name: string &default=""%): opaque of bloomfilter
+	%{
+	if ( k == 0 )
+		{
+		reporter->Error("number of hash functions must be non-negative");
+		return 0;
+		}
+	if ( cells == 0 )
+		{
+		reporter->Error("number of cells must be non-negative");
+		return 0;
+		}
+
+	size_t seed = Hasher::MakeSeed(name->Len() > 0 ? name->Bytes() : 0,
+                                 name->Len());
+	const Hasher* h = new DefaultHasher(k, seed);
+
+	return new BloomFilterVal(new BasicBloomFilter(h, cells));
+	%}
+
 ## Creates a counting Bloom filter.
 ##
 ## .. note:: A Bloom filter can have a name associated with it. In the future,
@@ -77,8 +118,8 @@ function bloomfilter_basic_init%(fp: double, capacity: count,
 ##
 ## Returns: A Bloom filter handle.
 ##
-## .. bro:see:: bloomfilter_basic_init bloomfilter_add bloomfilter_lookup
+## .. bro:see:: bloomfilter_basic_init bloomfilter_basic_init2 bloomfilter_add
-##    bloomfilter_clear bloomfilter_merge
+##    bloomfilter_lookup bloomfilter_clear bloomfilter_merge
 function bloomfilter_counting_init%(k: count, cells: count, max: count,
 				    name: string &default=""%): opaque of bloomfilter
 	%{
@@ -106,8 +147,9 @@ function bloomfilter_counting_init%(k: count, cells: count, max: count,
 ##
 ## x: The element to add.
 ##
-## .. bro:see:: bloomfilter_counting_init bloomfilter_basic_init loomfilter_lookup
+## .. bro:see:: bloomfilter_basic_init bloomfilter_basic_init2 
-##    bloomfilter_clear bloomfilter_merge
+##    bloomfilter_counting_init bloomfilter_lookup bloomfilter_clear 
+##    bloomfilter_merge
 function bloomfilter_add%(bf: opaque of bloomfilter, x: any%): any
 	%{
 	BloomFilterVal* bfv = static_cast<BloomFilterVal*>(bf);
@@ -132,8 +174,9 @@ function bloomfilter_add%(bf: opaque of bloomfilter, x: any%): any
 ##
 ## Returns: the counter associated with *x* in *bf*.
 ##
-## .. bro:see:: bloomfilter_counting_init bloomfilter_basic_init
+## .. bro:see:: bloomfilter_basic_init bloomfilter_basic_init2
-##    bloomfilter_add bloomfilter_clear bloomfilter_merge
+##    bloomfilter_counting_init bloomfilter_add bloomfilter_clear
+##    bloomfilter_merge
 function bloomfilter_lookup%(bf: opaque of bloomfilter, x: any%): count
 	%{
 	const BloomFilterVal* bfv = static_cast<const BloomFilterVal*>(bf);
@@ -159,8 +202,9 @@ function bloomfilter_lookup%(bf: opaque of bloomfilter, x: any%): count
 ##
 ## bf: The Bloom filter handle.
 ##
-## .. bro:see:: bloomfilter_counting_init bloomfilter_basic_init
+## .. bro:see:: bloomfilter_basic_init bloomfilter_counting_init2
-##    bloomfilter_add bloomfilter_lookup bloomfilter_merge
+##    bloomfilter_counting_init bloomfilter_add bloomfilter_lookup
+##    bloomfilter_merge
 function bloomfilter_clear%(bf: opaque of bloomfilter%): any
 	%{
 	BloomFilterVal* bfv = static_cast<BloomFilterVal*>(bf);
@@ -183,8 +227,9 @@ function bloomfilter_clear%(bf: opaque of bloomfilter%): any
 ##
 ## Returns: The union of *bf1* and *bf2*.
 ##
-## .. bro:see:: bloomfilter_counting_init bloomfilter_basic_init
+## .. bro:see:: bloomfilter_basic_init bloomfilter_basic_init2
-##    bloomfilter_add bloomfilter_lookup bloomfilter_clear
+##    bloomfilter_counting_init bloomfilter_add bloomfilter_lookup
+##    bloomfilter_clear
 function bloomfilter_merge%(bf1: opaque of bloomfilter,
 			    bf2: opaque of bloomfilter%): opaque of bloomfilter
 	%{

testing/btest/Baseline/bifs.bloomfilter/output

@@ -17,6 +17,8 @@ error: false-positive rate must take value between 0 and 1
 1
 1
 1
+1
+1
 2
 3
 3

testing/btest/bifs/bloomfilter.bro

@@ -15,6 +15,13 @@ function test_basic_bloom_filter()
   bloomfilter_add(bf_cnt, 0.5); # Type mismatch
   bloomfilter_add(bf_cnt, "foo"); # Type mismatch
 
+  # Alternative constructor.
+  local bf_dbl = bloomfilter_basic_init2(4, 10);
+  bloomfilter_add(bf_dbl, 4.2);
+  bloomfilter_add(bf_dbl, 3.14);
+  print bloomfilter_lookup(bf_dbl, 4.2);
+  print bloomfilter_lookup(bf_dbl, 3.14);
+
   # Basic usage with strings.
   local bf_str = bloomfilter_basic_init(0.9, 10);
   bloomfilter_add(bf_str, "foo");