Add role designation history

[ZhangTao1596]

I make this pr to let DesignateContract record historical role designation. So users can verify old messages.
Changes:

• DesignateContract add height and nodes when call DesignateAsRole
• Add GetDesignatedByRoleAndIndex to return designated nodes at specific index

@erikzhang @shargon @Tommo-L Please have a look.

[shargon]

Why do you want to verify old messages in the present, if they was verified already in the past?

[ZhangTao1596]

Why do you want to verify old messages in the present, if they was verified already in the past?

Not all messages signed by designated nodes saved in block, so these messages will not be sync with blockchain snapshot.
Take StateRoot for example, a node may receive StateRoot with index 100 when it already have sync block at 1000, It can't verify StateRoot with current snapshot. Designated nodes may change.

[shargon]

Wait for #1988 we need to store the history in different keys.

[roman-khimov]

Take StateRoot for example, a node may receive StateRoot with index 100 when it already have sync block at 1000, It can't verify StateRoot with current snapshot. Designated nodes may change.

Hmm... What if we're to include state root hash in the block header?

[ZhangTao1596]

Hmm... What if we're to include state root hash in the block header?

Only considering state root, if we put it into header, we do not need this.

[ProDog]

If there are two designate transactions in one block, can only get the last one?

[ZhangTao1596]

If there are two designate transactions in one block, can only get the last one?

What do you mean the last one?

[ProDog]

What do you mean the last one?

The last transaction's history.

[ZhangTao1596]

What do you mean the last one?

The last transaction's history.

Yes. Because designate transaction decide who are the nodes as specific role of next block. The last designate tx in same block will cover the previous.

[ProDog]

Tested OK.

neo> designate [{"type":"Integer","value":8},{"type":"Array","value":[{"type":"PublicKey","value":"02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b"},{"type":"PublicKey","value":"028bd1902c4d1419f002b821e6de653ddfd5358063208e426756398be6ffa3aac8"},{"type":"PublicKey","value":"0222d8515184c7d62ffa99b829aeb4938c4704ecb0dd7e340e842e9df121826343"},{"type":"PublicKey","value":"02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b"},{"type":"PublicKey","value":"02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b"}]}] 0xe19de267a37a71734478f512b3e92c79fc3695fa 0xe19de267a37a71734478f512b3e92c79fc3695fa
Invoking script with: 'DCECqepoQswMs7DyMXsHyFDePR4rJDqY7S1Wo/9MpmqvMwsMIQKp6mhCzAyzsPIxewfIUN49HiskOpjtLVaj/0ymaq8zCwwhAiLYUVGEx9Yv+pm4Ka60k4xHBOyw3X40DoQunfEhgmNDDCECi9GQLE0UGfACuCHm3mU939U1gGMgjkJnVjmL5v+jqsgMIQKp6mhCzAyzsPIxewfIUN49HiskOpjtLVaj/0ymaq8zCxXAGBLADA9kZXNpZ25hdGVBc1JvbGUMFGYmxmjw6Aa+yKJodaaguz7P/jp2QWJ9W1I='
VM State: HALT
Gas Consumed: 0.0101553
Result Stack: [{"type":"Boolean","value":true}]
Relay tx(no|yes): yes
Signed and relayed transaction with hash=0xc49bfc15ae51158ce758d334b6b844d5de976a4098e4994d34a1e84a227951e5

neo> designate [{"type":"Integer","value":8},{"type":"Array","value":[{"type":"PublicKey","value":"02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b"}]}] 0xe19de267a37a71734478f512b3e92c79fc3695fa 0xe19de267a37a71734478f512b3e92c79fc3695fa
Invoking script with: 'DCECqepoQswMs7DyMXsHyFDePR4rJDqY7S1Wo/9MpmqvMwsRwBgSwAwPZGVzaWduYXRlQXNSb2xlDBRmJsZo8OgGvsiiaHWmoLs+z/46dkFifVtS'
VM State: HALT
Gas Consumed: 0.0101481
Result Stack: [{"type":"Boolean","value":true}]
Relay tx(no|yes): yes
Signed and relayed transaction with hash=0x2ff1b554b3412db1e80a06a02005d393dfc366be622861837925ee4f30b0f69a

neo> get designated by index 8 86
Invoking script with: 'AFYYEsAMG2dldERlc2lnbmF0ZWRCeVJvbGVBbmRJbmRleAwUZibGaPDoBr7Iomh1pqC7Ps/+OnZBYn1bUg=='
VM State: HALT
Gas Consumed: 0.0200763
Designated:
02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b
028bd1902c4d1419f002b821e6de653ddfd5358063208e426756398be6ffa3aac8
0222d8515184c7d62ffa99b829aeb4938c4704ecb0dd7e340e842e9df121826343
02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b
02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b

neo> designate [{"type":"Integer","value":8},{"type":"Array","value":[{"type":"PublicKey","value":"0222d8515184c7d62ffa99b829aeb4938c4704ecb0dd7e340e842e9df121826343"}]}] 0xe19de267a37a71734478f512b3e92c79fc3695fa 0xe19de267a37a71734478f512b3e92c79fc3695fa
Invoking script with: 'DCECIthRUYTH1i/6mbgprrSTjEcE7LDdfjQOhC6d8SGCY0MRwBgSwAwPZGVzaWduYXRlQXNSb2xlDBRmJsZo8OgGvsiiaHWmoLs+z/46dkFifVtS'
VM State: HALT
Gas Consumed: 0.0101481
Result Stack: [{"type":"Boolean","value":true}]
Relay tx(no|yes): yes
Signed and relayed transaction with hash=0x2ffc8aeafcdc0b55f3c1964737249742304536a3087ca2292df067cefe94ae24

neo> designate [{"type":"Integer","value":8},{"type":"Array","value":[{"type":"PublicKey","value":"02a9ea6842cc0cb3b0f2317b07c850de3d1e2b243a98ed2d56a3ff4ca66aaf330b"}]}] 0xe19de267a37a71734478f512b3e92c79fc3695fa 0xe19de267a37a71734478f512b3e92c79fc3695fa
Invoking script with: 'DCECqepoQswMs7DyMXsHyFDePR4rJDqY7S1Wo/9MpmqvMwsRwBgSwAwPZGVzaWduYXRlQXNSb2xlDBRmJsZo8OgGvsiiaHWmoLs+z/46dkFifVtS'
VM State: HALT
Gas Consumed: 0.0101481
Result Stack: [{"type":"Boolean","value":true}]
Relay tx(no|yes): yes
Signed and relayed transaction with hash=0x828b8c62600221acce344554d2c1f95dd448e246e25e4c19cabbea85801d8ccd

neo> get designated by index 8 94
Invoking script with: 'AF4YEsAMG2dldERlc2lnbmF0ZWRCeVJvbGVBbmRJbmRleAwUZibGaPDoBr7Iomh1pqC7Ps/+OnZBYn1bUg=='
VM State: HALT
Gas Consumed: 0.0200763
Designated:
0222d8515184c7d62ffa99b829aeb4938c4704ecb0dd7e340e842e9df121826343