ns3::Hasher Class Reference

Generic Hash function interface. More...

#include "hash.h"

Public Member Functions
	Hasher ()
	Constructor using the default implementation. More...
	Hasher (Ptr< Hash::Implementation > hp)
	Constructor using the supplied implementation. More...
Hasher &	clear (void)
	Restore initial state. More...
uint32_t	GetHash32 (const char *buffer, const std::size_t size)
	Compute 32-bit hash of a byte buffer. More...
uint32_t	GetHash32 (const std::string s)
	Compute 32-bit hash of a string. More...
uint64_t	GetHash64 (const char *buffer, const std::size_t size)
	Compute 64-bit hash of a byte buffer. More...
uint64_t	GetHash64 (const std::string s)
	Compute 64-bit hash of a string. More...

Private Attributes
Ptr< Hash::Implementation >	m_impl
	Hash implementation. More...

Detailed Description

Generic Hash function interface.

This class provides a generic interface for computing hashes of buffers. Various getters return hashes of different lengths.

Call clear() between calls to the getter to reset the internal state and hash each buffer separately.

If you don't call clear() between calls to the getter you can hash successive buffers. The final return value will be the cumulative hash across all calls.

The choice of hash function can be made at construction by

Hasher hasher = Hasher ( Create<Hash::Function::Fnv1a> () );
uint32_t hash = Hasher.GetHash32 (data);

The available implementations are documented in Hash Functions. The default implementation is Murmur3. FNV1a is also available.

In addition to this class interface, global functions are defined which use the default hash implementation.

Internal:

Would be nice to offer longer hashes. uint128_t looks doable, except that our fallback int64x64_t implementation doesn't offer unsigned.

Longer hashes require returning a byte buffer of some sort, but our Buffer class seems a bit overkill for this case.

Definition at line 87 of file hash.h.

Constructor & Destructor Documentation

Hasher() [1/2]

ns3::Hasher::Hasher

(

)

Constructor using the default implementation.

Definition at line 35 of file hash.cc.

References m_impl, and NS_ASSERT.

Hasher() [2/2]

ns3::Hasher::Hasher

(

Ptr< Hash::Implementation >

hp

)

Constructor using the supplied implementation.

Parameters

[in]

hp

Ptr<Hash::Implementation> to the desired implementation.

Definition at line 41 of file hash.cc.

References m_impl, and NS_ASSERT.

Member Function Documentation

clear()

Hasher & ns3::Hasher::clear

(

void

)

Restore initial state.

Returning this Hasher allows code like this:

Hasher h;
h.GetHash32 (...);
...
h.clear ().GetHash64 (...);

Returns

This hasher.

Definition at line 48 of file hash.cc.

References m_impl.

Referenced by ns3::tests::IncrementalTestCase::DoHash(), UniqueTypeIdTestCase::DoRun(), ns3::tests::Fnv1aTestCase::DoRun(), ns3::tests::Murmur3TestCase::DoRun(), ns3::tests::Hash32FunctionPtrTestCase::DoRun(), ns3::tests::Hash64FunctionPtrTestCase::DoRun(), ns3::Hash::Example::Collider::GetHash(), ns3::IidManager::Hasher(), and ns3::Hash::Example::Dictionary::TimeOne().

GetHash32() [1/2]

uint32_t ns3::Hasher::GetHash32 ( const char *  buffer, const std::size_t  size  )

inline

Compute 32-bit hash of a byte buffer.

Call clear () between calls to GetHash32() to reset the internal state and hash each buffer separately.

If you don't call clear() between calls to GetHash32, you can hash successive buffers. The final return value will be the cumulative hash across all calls.

Parameters

[in]	buffer	Pointer to the beginning of the buffer.
[in]	size	Length of the buffer, in bytes.

Returns

32-bit hash of the buffer..

Definition at line 239 of file hash.h.

References m_impl, and NS_ASSERT.

Referenced by ns3::tests::IncrementalTestCase::DoHash(), UniqueTypeIdTestCase::DoRun(), ns3::tests::Fnv1aTestCase::DoRun(), ns3::tests::Murmur3TestCase::DoRun(), ns3::tests::Hash32FunctionPtrTestCase::DoRun(), ns3::Hash::Example::Collider::GetHash(), ns3::Hash32(), ns3::IidManager::Hasher(), and ns3::Hash::Example::Dictionary::TimeOne().

GetHash32() [2/2]

uint32_t ns3::Hasher::GetHash32 ( const std::string  s )

inline

Compute 32-bit hash of a string.

Call clear () between calls to GetHash32() to reset the internal state and hash each string separately.

If you don't call clear() between calls to GetHash32, you can hash successive strings. The final return value will be the cumulative hash across all calls.

Parameters

[in]

s

String to hash.

Returns

32-bit hash of the string.

Definition at line 255 of file hash.h.

References m_impl, and NS_ASSERT.

GetHash64() [1/2]

uint64_t ns3::Hasher::GetHash64 ( const char *  buffer, const std::size_t  size  )

inline

Compute 64-bit hash of a byte buffer.

Call clear () between calls to GetHash64() to reset the internal state and hash each buffer separately.

If you don't call clear() between calls to GetHash64, you can hash successive buffers. The final return value will be the cumulative hash across all calls.

Parameters

[in]	buffer	Pointer to the beginning of the buffer.
[in]	size	Length of the buffer, in bytes.

Returns

64-bit hash of the buffer.

Definition at line 247 of file hash.h.

References m_impl, and NS_ASSERT.

Referenced by ns3::tests::IncrementalTestCase::DoHash(), ns3::tests::Fnv1aTestCase::DoRun(), ns3::tests::Murmur3TestCase::DoRun(), ns3::tests::Hash64FunctionPtrTestCase::DoRun(), ns3::Hash::Example::Collider::GetHash(), and ns3::Hash64().

GetHash64() [2/2]

uint64_t ns3::Hasher::GetHash64 ( const std::string  s )

inline

Compute 64-bit hash of a string.

Call clear () between calls to GetHash64() to reset the internal state and hash each string separately.

If you don't call clear() between calls to GetHash64, you can hash successive strings. The final return value will be the cumulative hash across all calls.

Parameters

[in]

s

String to hash.

Returns

64-bit hash of the string.

Definition at line 263 of file hash.h.

References m_impl, and NS_ASSERT.

Member Data Documentation

m_impl

Ptr<Hash::Implementation> ns3::Hasher::m_impl

private

Hash implementation.

Definition at line 176 of file hash.h.

Referenced by clear(), GetHash32(), GetHash64(), and Hasher().

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The documentation for this class was generated from the following files:

• src/core/model/hash.h
• src/core/model/hash.cc