Ethereum block structure

1.

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. Blockchain is an important concept of bitcoin,

in essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of information of bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

most blockchain public chains are limited by scalability. The biggest feature of blockchain technology is decentralization, which requires that all accounts in the network need to deal with the accounting process. Distributed accounting has high security, low misoperation rate, political neutrality and correctness

however, blockchain technology embraces these features at the same time, sacrificing scalability, unable to meet the personalized supervision, and slightly insufficient in protecting data privacy. Moreover, with the increase of the number of ledger, the interaction delay will increase exponentially, that is to say, the more ledger in the blockchain network, the higher the delay

2.

what is Ethereum:

Ethereum is an innovation based on the application of technologies and concepts in bitcoin to computers. Ethereum itself imitates a lot of bitcoin technology to maintain the computer platform. Blockchain technology is one of them
Ethereum platform can safely run any program users want

advantages of Ethereum over other competitive currencies before Ethereum appeared, some digital currencies imitated bitcoin. However, these projects have their own shortcomings, they can only support one or several specific applications at the same time< However, the reason why Ethereum can surpass the limitations of these projects in the past is because of the core idea of Ethereum

what Ethereum wants to implement is a blockchain protocol with built-in programming language. Since it supports programming language, in theory, any blockchain application can be defined with this language, and then run on Ethereum's blockchain protocol as an application

The design of Ethereum is very flexible and adaptable

Ethereum target sets the advantages of blockchain technology, in order to add the advantages of blockchain, such as decentralization, openness and security, to almost all computing fields

blockchain applications of Ethereum

Ethereum has many blockchain applications, such as digital applications of gold and stocks, financial derivatives applications, DNS and digital authentication, etc

Ethereum has achieved more than 100 blockchain applications by many start-ups

Ethereum has also been closely watched by some financial institutions, banking consortia (such as R3), as well as large companies like Samsung, Deloitte, RWE and IBM. As a result, a number of blockchain applications such as simplified and automated financial transactions, merchant loyalty index tracking, and gift cards designed to achieve decentralization of electronic transactions have emerged

the relationship between Ethereum and blockchain:

Ethereum is a programmable blockchain

Ethereum does not give users a series of preset operations (such as bitcoin transaction), but allows users to create complex operations according to their own wishes

in this way, Ethereum can be used as a platform for various types of decentralized blockchain applications, including but not limited to cryptocurrency

like other blockchains, Ethereum also has a peer-to-peer network protocol. Ethereum blockchain database is maintained and updated by many nodes connected to the network. Each network node runs the Ethereum simulator and executes the same instructions. Therefore, people sometimes call Ethereum "world computer"

3. At the top of Ethereum is DAPP. It exchanges with the smart contract layer through Web3. JS. All smart contracts run on EVM (Ethereum virtual machine) and use RPC calls. Below EVM and RPC are the four core contents of Ethereum, including: blockchain, consensus algorithm, mining and network layer. Except DAPP, all other parts are in the Ethereum client. The most popular Ethereum client is geth (go Ethereum)

4. 1. Block declaration and thread safety

5. Data
block
,
extension
and
segment are different:
1. Block: the smallest unit of data block in Oracle, so data is ultimately stored in block. It is also called logical blocks or pages. Each operating system has its own block
size. The blocks here are Oracle's own, different from OS's blocks. By setting DB_ BLOCK_ Size sets the block of Oracle to several times of that of OS to rece unnecessary I / O. No matter whether the data stored in the block is table, index or clusterdata, the structure of the block is consistent
2. Extend: extend
is the logical minimum unit assigned to an object each time, which is composed of a certain number of continuous blocks. One or more extensions make up a segment
3. Segment: it is the set of extensions, which contains all the extensions of the specific logical storage organization contained in the table space. For example, an unpartitioned table, index and cluster are made into a segment, a partitioned index and a partition
of the table are made into a segment. For temporary
segment, it is mainly used for sorting and other operations. Only when the memory of the DB can not store the corresponding sorting operations and other better solutions can be found, can the temporary segment be created in the temporary table space.

6. Div elements are used to provide structure and background for block level content in HTML documents. Replace nested tags with HTML that contains only structured content, and search engines will search your web pages more efficiently

7. Because the structured mesh itself is a prism mesh, which is just a four prism mesh, while the boundary layer mesh generated by the tetrahedral unstructured mesh is a three prism mesh. Therefore, in my humble opinion, if you choose structured and unstructured regions for prism mesh generation, you should reconstruct the boundary layer mesh. It's just that the structured area can't be seen, or the generation of prism mesh is not set correctly. In fact, nodes that do not merge the two regions can also be calculated. In fluent, the interface will be automatically identified as two faces. As long as the two faces are set as interfaces in fluent, the data exchange needs of the two regions can be met

8. The solution to this problem:
1. Check whether the XML data call block is configured correctly
2. For partners who have just contacted Magento, we suggest a native version. Refer to the configuration and data call methods in the template to call the corresponding methods one by one
3. Advanced: by reconstructing the data interface of Magento and completing a set of Magento interface, you can understand all the data calling operations, code structure and database structure of Magento; Try to speed up Magento (key and difficult points). Now MEM is generally used to speed up Magento, but XML parsing is still very slow. The big framework structure makes it

I feel that it's better to give someone a packet of seasoning to make people want to eat fish. The code is not pasted. GOOD LUCK

9. struct ext2_super_block {
__le32 s_inodes_count; /* Inodes count */
__le32 s_blocks_count; /* Blocks count */
__le32 s_r_blocks_count; /* Reserved blocks count */
__le32 s_free_blocks_count; /* Free blocks count */
__le32 s_free_inodes_count; /* Free inodes count */
__le32 s_first_data_block; /* First Data Block */
__le32 s_log_block_size; /* Block size */
__le32 s_log_frag_size; /* Fragment size */
__le32 s_blocks_per_group; /* # Blocks per group */
__le32 s_frags_per_group; /* # Fragments per group */
__le32 s_inodes_per_group; /* # Inodes per group */
__le32 s_mtime; /* Mount time */
__le32 s_wtime; /* Write time */
__le16 s_mnt_count; /* Mount count */
__le16 s_max_mnt_count; /* Maximal mount count */
__le16 s_magic; /* Magic signature */
__le16 s_state; /* File system state */
__le16 s_errors; /* Behaviour when detecting errors */
__le16 s_minor_rev_level; /* minor revision level */
__le32 s_lastcheck; /* time of last check */
__le32 s_checkinterval; /* max. time between checks */
__le32 s_creator_os; /* OS */
__le32 s_rev_level; /* Revision level */
__le16 s_def_resuid; /* Default uid for reserved blocks */
__le16 s_def_resgid; /* Default gid for reserved blocks */
/*
* These fields are for EXT2_DYNAMIC_REV superblocks only.
*
* Note: the difference between the compatible feature set and
* the incompatible feature set is that if there is a bit set
* in the incompatible feature set that the kernel doesn't
* know about, it should refuse to mount the filesystem.
*
* e2fsck's requirements are more strict; if it doesn't know
* about a feature in either the compatible or incompatible
* feature set, it must abort and not try to meddle with
* things it doesn't understand...
*/
__le32 s_first_ino; /* First non-reserved inode */
__le16 s_inode_size; /* size of inode structure */
__le16 s_block_group_nr; /* block group # of this superblock */
__le32 s_feature_compat; /* compatible feature set */
__le32 s_feature_incompat; /* incompatible feature set */
__le32 s_feature_ro_compat; /* readonly-compatible feature set */
__u8 s_uuid[16]; /* 128-bit uuid for volume */
char s_volume_name[16]; /* volume name */
char s_last_mounted[64]; /* directory where last mounted */
__le32 s_algorithm_usage_bitmap; /* For compression */
/*
* Performance hints. Directory preallocation should only
* happen if the EXT2_COMPAT_PREALLOC flag is on.
*/
__u8 s_prealloc_blocks; /* Nr of blocks to try to preallocate*/
__u8 s_prealloc_dir_blocks; /* Nr to preallocate for dirs */
__u16 s_padding1;
/*
* Journaling support valid if EXT3_FEATURE_COMPAT_HAS_JOURNAL set.
*/
__u8 s_journal_uuid[16]; /* uuid of journal superblock */
__u32 s_journal_inum; /* inode number of journal file */
__u32 s_journal_dev; /* device number of journal file */
__u32 s_last_orphan; /* start of list of inodes to delete */
__u32 s_hash_seed[4]; /* HTREE hash seed */
__u8 s_def_hash_version; /* Default hash version to use */
__u8 s_reserved_char_pad;
__u16 s_reserved_word_pad;
__le32 s_default_mount_opts;
__le32 s_first_meta_bg; /* First metablock block group */
__u32 s_reserved[190]; /* Padding to the end of the block */
};

10. This is because for complex types such as structs, the compiler and processor will adopt byte alignment. To put it simply, variables are not stored arbitrarily in memory, but are stored according to certain rules, such as even number storage, multiple storage of 4, etc., which can improve the access efficiency.